document.write( "Question 529939: The sum of present ages of a father and his son is 80 years. when the fathers age was equal to the present age of the son, the sum of their ages was 40 years. find their present ages
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Algebra.Com's Answer #349826 by ptaylor(2198)\"\" \"About 
You can put this solution on YOUR website!
Let x=father's present age
\n" ); document.write( "Then 80-x=son's present age\r
\n" ); document.write( "\n" ); document.write( "Some t years ago, we know that father's age was equal to son's present age,or:
\n" ); document.write( " x-t=80-x collecting like terms we have:
\n" ); document.write( "2x-t=80--------------------------------------------------eq1
\n" ); document.write( "At that time, we also know that son's age was (80-x)-t
\n" ); document.write( "Now we are told that:
\n" ); document.write( "x-t+(80-x)-t=40, simplifying, we get
\n" ); document.write( "-2t+80=40
\n" ); document.write( "-2t=-40 or
\n" ); document.write( "t=20 , substituting t=20 into eq1, we have
\n" ); document.write( "2x-20=80
\n" ); document.write( "2x=100
\n" ); document.write( "x=50 -----------father's present age
\n" ); document.write( "80-x=80-50=30-----------son's present age\r
\n" ); document.write( "\n" ); document.write( "CK
\n" ); document.write( "50+30=80
\n" ); document.write( "80=80
\n" ); document.write( "and
\n" ); document.write( "(50-20)+(30-20)=40
\n" ); document.write( "40=40\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor \n" ); document.write( "
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