document.write( "Question 587274: Father: When I was your age, you were 3 years old.\r
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Algebra.Com's Answer #374043 by Edwin McCravy(20060)\"\" \"About 
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Father: When I was your age, you were 3 years old.\r
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document.write( "Suppose the Father is x years older than the son.\r\n" );
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document.write( "Then x years ago the Father was the Son's present age, and the son was 3. \r\n" );
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document.write( "F - x = S\r\n" );
document.write( "S - x = 3\r\n" );
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document.write( "And x years from now the son will be the father's age and the father will\r\n" );
document.write( "be 63.\r\n" );
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document.write( "S + x = F\r\n" );
document.write( "F + x = 63\r\n" );
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document.write( "So we have this system:\r\n" );
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document.write( "F - x = S\r\n" );
document.write( "S - x = 3\r\n" );
document.write( "S + x = F\r\n" );
document.write( "F + x = 63\r\n" );
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document.write( "The first and third equations are equivalent so we can ignore the\r\n" );
document.write( "third equation:\r\n" );
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document.write( "F - x = S\r\n" );
document.write( "S - x = 3\r\n" );
document.write( "F + x = 63\r\n" );
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document.write( "Solve that system and you'll get F = 43, S = 23, x = 20\r\n" );
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document.write( "Checking: 20 years ago the father was 43-20 or 23, which is the son's present\r\n" );
document.write( "age.  20 years ago the son was 23-20 or 3.  20 years from now the son will\r\n" );
document.write( "be 23+20 or 43, the Father's present age, and 20 years from now the father will be 43+20 or 63.\r\n" );
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document.write( "Edwin
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