document.write( "Question 324481: Five years ago father's age was seven times his sons age. Ten years hence their ages will be in the ratio of 5 : 2. Find their present ages \n" ); document.write( "
Algebra.Com's Answer #232234 by nerdybill(7384)\"\" \"About 
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Five years ago father's age was seven times his sons age. Ten years hence their ages will be in the ratio of 5 : 2. Find their present ages
\n" ); document.write( "Let x = father's age
\n" ); document.write( "and y = son's age
\n" ); document.write( ".
\n" ); document.write( "From:\"Five years ago father's age was seven times his sons age.\"
\n" ); document.write( "x-5 =7(y-5)
\n" ); document.write( "x-5 =7y-35
\n" ); document.write( "x-7y = -30 equation 1
\n" ); document.write( ".
\n" ); document.write( "From:\"Ten years hence their ages will be in the ratio of 5 : 2.\"
\n" ); document.write( "(x+10)/(y+10) = 5/2
\n" ); document.write( "2(x+10) = 5(y+10)
\n" ); document.write( "2x+20 = 5y+50
\n" ); document.write( "2x-5y = 30 equation 2
\n" ); document.write( ".
\n" ); document.write( "x-7y = -30
\n" ); document.write( "2x-5y = 30
\n" ); document.write( ".
\n" ); document.write( "Multiply the top equation by -2 and add to the second:
\n" ); document.write( "-2x+14y = 60
\n" ); document.write( " 2x-5y = 30
\n" ); document.write( "-------------
\n" ); document.write( " 9y = 90
\n" ); document.write( "y = 10 years old (son's age)
\n" ); document.write( ".
\n" ); document.write( "Father's age:
\n" ); document.write( "x-7y = -30
\n" ); document.write( "x-7(10) = -30
\n" ); document.write( "x-70 = -30
\n" ); document.write( "x = 40 years old (father's age)\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
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