document.write( "Question 587382: Jack is 17 years old and his sister is four years younger than he is. In how many years will the sum of their ages be triple what the sum of their ages is now? \n" ); document.write( "

Algebra.Com's Answer #374113 by richwmiller(17219) $\"\"$ $\"About$

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s=j-4
\n" ); document.write( "j=17\r
\n" ); document.write( "\n" ); document.write( "3*(j+s)=(j+s+2x)
\n" ); document.write( "j = 17, s = 13, x = 30\r
\n" ); document.write( "\n" ); document.write( "In 30 years their ages will add up to 90
\n" ); document.write( "now their ages add up to 30\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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