document.write( "Question 878521: Three years ago, X's age was double of Y's. Seven year hence the sum of their ages will be 83 years. What is the age of X today? \n" ); document.write( "

Algebra.Com's Answer #530017 by JulietG(1812) $\"\"$ $\"About$

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x-3 = 2(y-3) [Three years ago, X's age was double of Y's.]
\n" ); document.write( "x-3 = 2y-6
\n" ); document.write( "Add 3 to each side
\n" ); document.write( "x = 2y-3
\n" ); document.write( "(x+7) + (y+7) = 83 [Seven year hence the sum of their ages will be 83 years]
\n" ); document.write( "Let's work the second equation.
\n" ); document.write( "x+y+14 = 83
\n" ); document.write( "subtract 14 from each side
\n" ); document.write( "x+y = 69
\n" ); document.write( "Substitute the value of x from the first equation into the second.
\n" ); document.write( "(2y-3) + y = 69
\n" ); document.write( "3y - 3 = 69
\n" ); document.write( "Add 3 to each side
\n" ); document.write( "3y = 72
\n" ); document.write( "Divide each side by 3
\n" ); document.write( "y = 24
\n" ); document.write( ".
\n" ); document.write( "If y is 24, then x is 69 - 24, or 45.
\n" ); document.write( ".
\n" ); document.write( "Let's plug it in to make certain.
\n" ); document.write( "3 years ago, x's age was double y's. Three years ago, x would have been 42. Y would have been 21. That is indeed double.
\n" ); document.write( "Success! \n" ); document.write( "

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