SOLUTION: A boy is one-fifth of his father's age. In 3years time the sum of the boy's and father's age is 72. What is the age of both of them

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Question 1157205: A boy is one-fifth of his father's age. In 3years time the sum of the boy's and father's age is 72. What is the age of both of them
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39620) About Me  (Show Source):
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b, the boy
5b, the father

The description: b%2B3%2B5b%2B3=72


steps
6b=72-6
6b=66
highlight%28b=11%29

highlight%285b=55%29-------father

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Using logical reasoning and some simple mental arithmetic, instead of formal algebra (if a formal algebraic solution is not required!)...

The boy is 1/5 of his father's age --> the boy is 1/6 of the SUM of their ages; the father is 5/6 of the SUM.

The sum of their ages 3 years from now is 72 --> the sum of their ages now is 72-2*3 = 66.

The son's age is 1/6 of 66, which is 11; the father is 5/6 of 66, which is 55.

ANSWERS: 11 and 55