document.write( "Question 1190005: A is 12 years older than B; 12 years ago he was twice as old as B then was. How old is A now, and how many years ago is it since he was three times as old as B then was
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Algebra.Com's Answer #821545 by ankor@dixie-net.com(22740)\"\" \"About 
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A is 12 years older than B;
\n" ); document.write( " a = b + 12
\n" ); document.write( " a - b = 12
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\n" ); document.write( " 12 years ago he was twice as old as B then was.
\n" ); document.write( "a - 12 = 2(b - 12)
\n" ); document.write( "a - 12 = 2b - 24
\n" ); document.write( "a - 2b = -24 + 12
\n" ); document.write( "a - 2b = -12
\n" ); document.write( "use elimination on these two equations
\n" ); document.write( "a - b = 12
\n" ); document.write( "a - 2b =-12
\n" ); document.write( "----------------subtraction eliminates a, find b
\n" ); document.write( "0 + b = 24
\n" ); document.write( "B is 24 yrs old
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\n" ); document.write( " How old is A now,
\n" ); document.write( "\"A is 12 years older than B\"
\n" ); document.write( "a = 12 + 24
\n" ); document.write( "a = 36 yrs is A
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\n" ); document.write( " how many years ago is it since he was three times as old as B then was
\n" ); document.write( "let y = no. of years for this to be true
\n" ); document.write( "36 - y = 3(24 - y)
\n" ); document.write( "36 - y = 72 - 3y
\n" ); document.write( "-t + 3y = 72 - 36
\n" ); document.write( "2y = 36
\n" ); document.write( "y = 36/2
\n" ); document.write( "y = 18 yrs ago A was 3 times as old a B
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