document.write( "Question 935064: The fairly family are great mathematicians. When asked how old everyone was the family replied, “Our family of two adults and three children is exactly 123 years old altogether”. The father and son’s ages, when added are 59, which is 5 years less than the mother and the twin girls. The father is three years older than the mother, while the son is three years older than the girls. can you work out each persons age \n" ); document.write( "
Algebra.Com's Answer #568183 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Let:\r\n" );
document.write( "F = father's age\r\n" );
document.write( "M = mother's age\r\n" );
document.write( "S = son's age\r\n" );
document.write( "D = each of the twin daughter's age\r\n" );
document.write( "

\n" ); document.write( ">>Our family of two adults and three children is exactly 123 years<<
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document.write( "F+M+S+2D = 123\r\n" );
document.write( "

\n" ); document.write( ">>The father and son’s ages, when added are 59,<<
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document.write( "F+S = 59\r\n" );
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\n" ); document.write( "which [59] is 5 years less than the mother and the twin girls.
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document.write( "59 = M+2D-5\r\n" );
document.write( "64 = M+2D\r\n" );
document.write( "

\n" ); document.write( ">>The father is three years older than the mother,<<
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document.write( "F = M+3\r\n" );
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\n" ); document.write( ">>the son is three years older than the girls.<<
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document.write( "S = D+3 \r\n" );
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document.write( "So we have this system of 5 equations in 4 unknowns.\r\n" );
document.write( "That means we were given more information that we needed.\r\n" );
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document.write( "\"system%28F%2BM%2BS%2B2D=123%2C+F%2BS=59%2C+64=M%2B2D%2C+F=M%2B3%2C+S=D%2B3%29\"\r\n" );
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document.write( "Substitute D+3 for S in the first 4 equations and simplify:\r\n" );
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document.write( "\"system%28F%2BM%2B3D%2B2D=120%2C+F%2BD=56%2C+64=M%2B2D%2C+F=M%2B3%29\"\r\n" );
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document.write( "Substitute M+3 for F in the first 3 equations and simplify:\r\n" );
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document.write( "\"system%282M%2B5D=117%2C+M%2BD=53%2C+64=M%2B2D%29\"\r\n" );
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document.write( "Solve the middle equation for M:  M=53-D. Substitute in the\r\n" );
document.write( "other 2 equations:\r\n" );
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document.write( "\"system%282%2853-D%29%2B5D=117%2C+64=53-D%2B2D%29\"\r\n" );
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document.write( "\"system%28D=11%2C+11=D%29\"\r\n" );
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document.write( "So the twin daughters are 11 each.\r\n" );
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document.write( "M=53-D = 53-11 = 42, so the mother is 42.\r\n" );
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document.write( "F=M+3 = 42+3 = 45, so the father is 45.\r\n" );
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document.write( "S=D+3 = 11+3 = 14, so the son is 14.\r\n" );
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document.write( "Edwin

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