document.write( "Question 840089: In 5 years, Tom will be twice as old as Cindy. 13 years ago, he was three times as old as Cindy. How many years ago was Tom four times as old as Cindy?
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Algebra.Com's Answer #506069 by ankor@dixie-net.com(22740)\"\" \"About 
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let t = Tom's present age
\n" ); document.write( "let c = Cindy's age
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\n" ); document.write( "Write an equation for each statement. simplify as much as possible
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\n" ); document.write( "In 5 years, Tom will be twice as old as Cindy.
\n" ); document.write( "t + 5 = 2(c+5)
\n" ); document.write( "t + 5 = 2c + 10
\n" ); document.write( "t = 2c + 10 - 5
\n" ); document.write( "t = 2c + 5
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\n" ); document.write( "13 years ago, he was three times as old as Cindy.
\n" ); document.write( "t - 13 = 3(c-13)
\n" ); document.write( "t - 13 = 3c - 39
\n" ); document.write( "t = 3c - 39 + 13
\n" ); document.write( "t = 3c - 26
\n" ); document.write( "Find their present ages, in the 1st equation replace t with (3c-26)
\n" ); document.write( "3c - 26 = 2c + 5
\n" ); document.write( "3c - 2c = 5 + 26
\n" ); document.write( "c = 31 yrs is Cindy's present age
\n" ); document.write( "and
\n" ); document.write( "t = 2(31) + 5
\n" ); document.write( "t = 67 yrs is Tom's
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\n" ); document.write( " How many years ago was Tom four times as old as Cindy?
\n" ); document.write( "let y = no. of years for this to be true
\n" ); document.write( "67 - y = 4(31-y)
\n" ); document.write( "67 - y = 124 - 4y
\n" ); document.write( "-y + 4y = 124 - 67
\n" ); document.write( "3y = 57
\n" ); document.write( "y = 57/3
\n" ); document.write( "y = 19 yrs ago
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\n" ); document.write( "I'll let you check this out in the last statement.
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