<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>0012 - Disclosure - Convertible Debts</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>From2013-01-01to2013-06-30</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001420421</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="6 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>MSTG_ConvertibleDebtsAbstract</ElementName><ElementPrefix>MSTG_</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Convertible Debts</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_ShortTermDebtTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="From2013-01-01to2013-06-30" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;The
Company has issued for aggregate consideration of $25,000 a convertible note to a related party, a stockholder of the Company.
This note bears interest at the imputed IRS rate of .0054% per annum and is due September 28, 2011. The note is convertible into
common stock of the Company at the rate of $.25 per share. In addition, upon conversion to common stock at maturity date, the
Company will issue a 2-year warrant to purchase 100,000 shares of the Company's common stock at an exercise price of $.50 per
share. The Company has recorded a beneficial conversion in the amount of $19,723 to reflect the fair value of the convertible
debt and a corresponding increase to additional paid-in capital. As of December 31, 2011, the convertible note was repaid in full.&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;&amp;#160;&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;On
February 15, 2013, the Company issued a convertible note of $45,000. The note accrues interest at 12% per annum and matured on
April 16, 2013. The note is convertible into shares of Company&amp;#146;s common stock at a conversion price of $0.01 per share. The
difference between the effective conversion price of the convertible notes into shares of the Company&amp;#146;s common stock, and
the fair value of the Company&amp;#146;s common stock on the date of issuance of the convertible notes, resulted in a beneficial conversion
feature in the amount of $16,875. In addition, upon the issuance of convertible note, the Company issued 2,500,000 shares of the
Company's common stocks (See note 7).&amp;#160;The Company has recorded a debt discount in the amount of $28,125 to reflect the value
of the common stocks as a reduction to the carrying amount of the convertible debt and a corresponding increase to common stocks
and additional paid-in capital.&amp;#160;The total discount of $45,000 was amortized over the term of the debt.&amp;#160;&amp;#160;Amortization
for the six months ended June 30, 2013 was $45,000. The Company was not able to repay the loan on the maturity date, however,
the principal balance of $45,000 was repaid on June 28, 2013. At June 30, 2013, the Company owes accrued interest of $1,586 to
the Note Holder.&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;&amp;#160;&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;On
February 28, 2013, the Company issued two convertible notes totaling $200,000. The notes accrued interest at 12% per annum and
matured on April 27, 2013.&amp;#160;The notes are convertible into shares of Company&amp;#146;s common stocks at a conversion price of
$0.01 per share. The difference between the effective conversion price of the convertible notes into shares of the Company&amp;#146;s
common stock, and the fair value of the Company&amp;#146;s common stock on the date of issuance of the convertible notes, resulted
in a beneficial conversion in the amount of $200,000. The total discount of $200,000 was amortized over the term of the debt.
Total amortization for the two convertible notes for the six months ended June 30, 2013 was $200,000. As of June 30, 2013, the
Company was not able to repay the loan on the maturity date, and the principal balance of $200,000 and accrued interest of $8,022
are in default. The note does not include any additional fees or penalties due to the loan being in default. The notes were converted
into 20,000,000 shares of Company&amp;#146;s common stock to satisfy the debt of $200,000 on July 8, 2013.&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;&amp;#160;&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;On
April 20, 2013, the Company issued a convertible note of $100,000. The note accrued interest at 12% per annum and matured on June
19, 2013.&amp;#160;The note is convertible into shares of Company&amp;#146;s common stocks at a conversion price of $0.01 per share. The
difference between the effective conversion price of the convertible notes into shares of the Company&amp;#146;s common stock, and
the fair value of the Company&amp;#146;s common stock on the date of issuance of the convertible notes, resulted in a beneficial conversion
in the amount of $100,000. The total discount of $100,000 was amortized over the term of the debt. Total amortization for the
convertible note for the six months ended June 30, 2013 was $100,000. As of June 30, 2013, the Company was not able to repay the
loan on the maturity date, and the principal balance of $100,000 and accrued interest of $2,334 are in default. The note does
not include any additional fees or penalties due to the loan being in default. The notes were converted into 10,000,000 shares
of Company&amp;#146;s common stock was made to satisfy the debt of $100,000 on July 8, 2013.&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;&amp;#160;&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;On
June 28, 2013, the Company issued a convertible note of $1,350,000. The Note matures on June 28, 2016 and is secured by a lien
on all the assets of the Company. The interest is payable by 50 ounces of gold produced by the Company on a monthly basis commencing
on August 28, 2013. If the 50 ounces of gold are not available, the gold shall be made available at the next monthly interest
date. As of June 30, 2013, the interest expense is $4,136.&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&lt;font style="font: 10pt Times New Roman, Times, Serif"&gt;&amp;#160;&lt;/font&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;The note is convertible
into shares of Company&amp;#146;s common stock at a conversion price of $0.10 per share. The Company also issued a 5-year warrant
to purchase 13,500,000 shares of common stock at an exercise price of $0.15 per share. (See note 7).&amp;#160;In addition, the Company
agreed to sell to the Note holder on a monthly basis commencing August 28, 2013, 100 ounces of gold per month for a purchase price
of $500 per ounce. If an ounce of gold as reported on Kitco.com is less than $1,000 an ounce when the gold is to be delivered
to the Buyer, the purchase price of the gold shall be $400 per ounce. The agreement shall survive until an aggregate of 3,500
ounces of gold have been purchased by the Note holder. The Company has recorded a contract settlement liability in the amount
of $2,590,000 to reflect the value of the 3,500 ounces of gold committed to purchase as a reduction to the carrying amount of
the convertible debt.&amp;#160;The total discount of $1,300,000 will be amortized over the term of the debt.&amp;#160;&amp;#160;Amortization
for the six months ended June 30, 2013 was $2,500.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&amp;#160;The Company also agreed
to file a registration statement to register for re-sale the shares issuable upon conversion of the Note and the shares underlying
the Warrant . If the registration statement is not declared effective by the Securities and Exchange Commission by August 28,
2013, the Company shall pay the Buyer as liquidated damages 3% of the liquidated value of the Conversion Shares for each 30 day
period subsequent to August 28, 2013. As of June 30, 2013, the Company has accrued liquidated damage expense of $81,000.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-indent: 1in; text-align: justify"&gt;As of
June 30, 2013, the Company has received $1,300,000 of the proceeds from the convertible note. The remaining $50,000 was funded
in July 2013.&lt;/p&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for short-term debt.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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 -Publisher SEC

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