1.  A father tells his son, "I was of your present age when you were born". If the father is 36 now, how old was the boy five years back ?
A. 13
B. 15
C. 17
D. 20

Answer: Option A

Explanation:

Let the father's age be x and the son's age be y.

Then, x - y = y or x = 2y,

Now, x = 36. So, 2y = 36 or y = 18.

Therefore Son's present age = 18 years.

So, son's age 5 years ago = 13 years.