A man is four times as old as his son. In five years he will be only three times as old as his son. What is the man's present age?

1 Answer
May 1, 2018

Man's present age : 40 years old.

Explanation:

Let man's age = a
Let son's age = b

Since a man is 4 times as old as his son, therefore
a = 4b

In 5 years, he will only be 3 times as old as his son, therefore
a+5 = 3(b+5)

Apply substitution method :
4b + 5 = 3b + 15

b = 10

a = 40