document.write( "Question 780863: my age plus my son age is equal to my fathers age which is 78 years old.when i was my son age he was just a quarter as old as i am now.how old am i? \n" ); document.write( "

Algebra.Com's Answer #475935 by Edwin McCravy(20056) $\"\"$ $\"About$

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my age plus my son age is equal to my fathers age which is 78 years old.
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document.write( "Let My age = M\r\n" );
document.write( "Let my son's age = S.  So\r\n" );
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document.write( "M + S = 78\r\n" );
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\n" ); document.write( "when I was my son age
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document.write( "Let that be x years ago, which means \r\n" );
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document.write( "M - x = S  and my son was S - x\r\n" );
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\n" ); document.write( "he was just a quarter as old as i am now.
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document.write( "S - x = M\r\n" );
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document.write( "So we have three equations in 3 unknowns:\r\n" );
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document.write( "M + S = 78\r\n" );
document.write( "M - x = S\r\n" );
document.write( "S - x = M\r\n" );
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document.write( "Clear the fraction in the third one:\r\n" );
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document.write( "M + S = 78\r\n" );
document.write( "M - x = S\r\n" );
document.write( "4S - 4x = M\r\n" );
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document.write( "Line up the letters and symbols:\r\n" );
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document.write( " M +  S     = 78\r\n" );
document.write( " M -  S - x =  0\r\n" );
document.write( "-M - 4S - 4x = 0 \r\n" );
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document.write( "Solve that system of equations and get\r\n" );
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document.write( "M = 48, S = 30, x = 18\r\n" );
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\n" ); document.write( "how old am i?
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document.write( "So I am 48.\r\n" );
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document.write( "Checking:\r\n" );
document.write( "

\n" ); document.write( "my age plus my son age is equal to my father's age which is 78 years old.
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document.write( "48+30 = 78 that checks\r\n" );
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\n" ); document.write( "when I was my son age,
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document.write( "that is 18 years ago when I was 48-18 or 30. That checks.\r\n" );
document.write( "

\n" ); document.write( "he was just a quarter as old as i am now.
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document.write( "18 years ago he was 30-18 or 12, which is just a quarter of 48.\r\n" );
document.write( "That checks. \r\n" );
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document.write( "Edwin

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