document.write( "Question 835727: Bill is 2 years older than his brother and 5 years younger than his sister. 5 years ago the sum of the ages of Bill and his bbrother was equal to their sister's age then. How old is Bill now \n" ); document.write( "
Algebra.Com's Answer #503820 by ankor@dixie-net.com(22740)\"\" \"About 
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Let x = Bill's age
\n" ); document.write( "Let y = brother's age
\n" ); document.write( "let z = sister's age
\n" ); document.write( ":
\n" ); document.write( "Bill is 2 years older than his brother
\n" ); document.write( "x = y + 2
\n" ); document.write( "or
\n" ); document.write( "y = (x-2)
\n" ); document.write( "and 5 years younger than his sister.
\n" ); document.write( "x = z - 5
\n" ); document.write( "or
\n" ); document.write( "z = (x+5)
\n" ); document.write( ":
\n" ); document.write( "5 years ago the sum of the ages of Bill and his brother was equal to their sister's age then.
\n" ); document.write( "(x-5) + (y-5) = (z-5)
\n" ); document.write( "x + y = z - 5 + 10
\n" ); document.write( "x + y = z + 5
\n" ); document.write( "replace y with (x-2); replace z with (x+5)
\n" ); document.write( "x + (x-2) = (x+5) + 5
\n" ); document.write( "2x = x + 5 + 5 + 2
\n" ); document.write( "2x - x = 12
\n" ); document.write( "x = 12 is Bill's age
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