document.write( "Question 121550: im not very good at algebra. Joe's dad s 2 times joe's age. 7 years ago, he was 3 times older than joe. find both's ages. \n" ); document.write( "
Algebra.Com's Answer #89204 by Earlsdon(6294)\"\" \"About 
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Let D = Dad's present age and J = Joe's present age.
\n" ); document.write( "From the problem description you can write:
\n" ); document.write( "D = 2J \"Dad is two times Joe's age\". Substitute this value of D into the second equation and solve for J.
\n" ); document.write( "D-7 = 3(J-7) \"Seven years ago (that's -7), Dad was three times Joe's age\".
\n" ); document.write( "2J-7 = 3(J-7) Simplify.
\n" ); document.write( "2J-7 = 3J-21 Subtract 2J from both sides.
\n" ); document.write( "-7 = J-21 Add 21 to both sides.
\n" ); document.write( "14 = J
\n" ); document.write( "Joe's age is 14
\n" ); document.write( "D = 2J
\n" ); document.write( "D = 2(14)
\n" ); document.write( "D = 28
\n" ); document.write( "Dad's age is 28
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