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
Answer by ptaylor(2198)   (Show Source):
You can put this solution on YOUR website! Let x=father's present age
Then 80-x=son's present age
Some t years ago, we know that father's age was equal to son's present age,or:
x-t=80-x collecting like terms we have:
2x-t=80--------------------------------------------------eq1
At that time, we also know that son's age was (80-x)-t
Now we are told that:
x-t+(80-x)-t=40, simplifying, we get
-2t+80=40
-2t=-40 or
t=20 , substituting t=20 into eq1, we have
2x-20=80
2x=100
x=50 -----------father's present age
80-x=80-50=30-----------son's present age
CK
50+30=80
80=80
and
(50-20)+(30-20)=40
40=40
Hope this helps---ptaylor
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