document.write( "Question 829885: On his birthday last year John said \"My age is the sum of the digits of the year in which I was born\". How old is John?\r
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Algebra.Com's Answer #500205 by ankor@dixie-net.com(22740)\"\" \"About 
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On his birthday last year John said
\n" ); document.write( " \"My age is the sum of the digits of the year in which I was born\".
\n" ); document.write( " How old is John?
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\n" ); document.write( "Assuming last year was 2013
\n" ); document.write( "Assuming the first two digits of the year he was born is 19, their sum = 10
\n" ); document.write( "Let a = 3rd digit of the year he was born
\n" ); document.write( "Let b = 4th digit of the year he was born
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\n" ); document.write( "2013 - (1900+10a+b) = 1+9+a+b
\n" ); document.write( "2013 - 1900 - 10a - b = 10 + a + b
\n" ); document.write( "113 - 10a - a - b - b = 10
\n" ); document.write( "113 - 11a - 2b = 10
\n" ); document.write( "-2b = 11a + 10 - 113
\n" ); document.write( "-2b = 11a - 103
\n" ); document.write( "Divide both sides by -2
\n" ); document.write( "b = -5.5a + 51.5
\n" ); document.write( "Only integer solution a=9, b=2
\n" ); document.write( "He was born in 1992, sum of the digits 21, which is his age
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\n" ); document.write( "Check this 2013-1992 = 21 \n" ); document.write( "
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