document.write( "Question 1154263: Twice my age plus three times my sister's age is 86. Three times my age plus four times my sister's age is 120. How old am I?
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Algebra.Com's Answer #776674 by MathTherapy(10552) $\"\"$ $\"About$

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\n" ); document.write( "Twice my age plus three times my sister's age is 86. Three times my age plus four times my sister's age is 120. How old am I?
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Let my age be M and my sister's, S
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document.write( "Then we get: 2M + 3S = 86 ------- eq (i)	
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document.write( "Also, 3M + 4S = 120 ------ eq (ii)	
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document.write( "M + S = 34 ----- Subtracting eq (i) from eq (ii)
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document.write( "S = 34 - M	
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document.write( "2M + 3(34 - M) = 86 ------ Substituting 34 - M for S in eq (i)
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document.write( "2M + 102 - 3M = 86
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document.write( "2M - 3M = 86 - 102
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document.write( "- M = - 16 
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document.write( "M, or my age is:  \n" );
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