Question

A man is four times as old as his son. After 20 years, he will be twice as old as his son at that time. Find their present ages.

Answer 1

Let the present age of the son = x years

Present age of the father = 4x years

After 20 years,

Son’s age will be (x + 20) years

and Father’s age will be (4x + 20) years

According to the condition,

4x + 20 = 2 (x + 20)

4x + 20 = 2x + 40

4x – 2x = 40 – 20

2x = 20

⇒ x = 10

∴ Present age of the son = 10 years and Present age of the father = 4×10 years = 40 years