document.write( "Question 1112805: when john was marys age she was 7. when shes his age he will be 73. What is John's age? \n" ); document.write( "
Algebra.Com's Answer #727855 by ankor@dixie-net.com(22740)\"\" \"About 
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when john was marys age she was 7.
\n" ); document.write( " when shes his age he will be 73.
\n" ); document.write( " What is John's age?
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\n" ); document.write( "let j = John's present age
\n" ); document.write( "let d = the difference in their ages
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\n" ); document.write( "\"when John was Mary's age she was 7.
\n" ); document.write( "j = d + 7
\n" ); document.write( "or
\n" ); document.write( "j - d = 7
\n" ); document.write( "\"when she's his age he will be 73.\"
\n" ); document.write( "j + d = 73
\n" ); document.write( "Use elimination with these two equations
\n" ); document.write( "j - d = 7
\n" ); document.write( "j + d = 73
\n" ); document.write( "2j = 80
\n" ); document.write( "j = 80/2
\n" ); document.write( "j = 40 yrs is John's age
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