SOLUTION: A boy is one-fifth of his father age. In three years time, the sum of their ages will be 72. How old are they now?

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Question 1193345: A boy is one-fifth of his father age. In three years time, the sum of their ages will be 72. How old are they now?
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Informally....

Since the sum of their ages 3 years from now will be 72, the sum of their ages now is 66.

We need to divide those 66 years into two parts in the ratio 5:1; their ages are 55 and 11.

Formally....

x = son's age now
5x = father's age now
x+3 = son's age 3 years from now
5x+3 = father's age 3 years from now

The sum of their ages 3 years from now will be 72:

%28x%2B3%29%2B%285x%2B3%29=72
6x%2B6=72
6x=66
x=11

ANSWER: The son's age now is x=11; the father's age now is 5x=55.