A father said to his child, "I was as old as you are at the time of your birth". If the father's age is 48 years now, the child's age six years back was:

18 Years

Let the present age of son = x years

Present age of father is = 48 years.

Father's age at the time of birth of son = (48 -x) years.

ATQ,

Father's age at the time of birth of son = Present age of son

⇒ (48 - x) = x

⇒ 2x = 48

⇒ x = 24

Therefore, present age of son = 24 years

Son's age six years back = 24 - 6 = 18 years.