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 #89203 by Fombitz(32388) $\"\"$ $\"About$

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Let's use D to stand for Joe's Dad's age.
\n" ); document.write( "Let's use J to stnad for Joe's age.
\n" ); document.write( "1. $\"D=2J\"$
\n" ); document.write( "Seven years ago, both Joe and his Dad were 7 years younger (subtract 7).
\n" ); document.write( "2. $\"D-7=3%28J-7%29\"$
\n" ); document.write( "Substitute 1 into 2 and solve for J.
\n" ); document.write( " $\"D-7=3%28J-7%29\"$
\n" ); document.write( " $\"2J-7=3%28J-7%29\"$
\n" ); document.write( " $\"2J-7=3J-21%29\"$ Distributive property.
\n" ); document.write( " $\"2J-7-3J=3J-21-3J%29\"$ Subtract 3J from both sides.
\n" ); document.write( " $\"%282J-3J%29-7=%283J-3J%29-21\"$
\n" ); document.write( " $\"%28-J%29-7=%280%29-21\"$
\n" ); document.write( " $\"-J-7=-21\"$
\n" ); document.write( " $\"-J-7%2B7=-21%2B7\"$ Add 7 to both sides of the equation.
\n" ); document.write( " $\"-J=-14\"$
\n" ); document.write( " $\"J=14\"$ Multiply both sides by (-1)
\n" ); document.write( "Now you have Joe's age you can find his Dad's age using either 1 or 2.
\n" ); document.write( "1. $\"D=2J\"$
\n" ); document.write( " $\"D=2%2814%29\"$
\n" ); document.write( " $\"D=28\"$
\n" ); document.write( "Joe is 14 years old, his dad is 28 years old.(D=2J)
\n" ); document.write( "Seven years ago, Joe was 7, his Dad 21. (D-7=3(J-7)) \n" ); document.write( "

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