Correct Answer - Option 4 : 25
The ratio of the present ages of A and B is 3 : 5.
Let the common multiple be x.
So, the present age of A = 3x and the present age of B = 5x.
The sum of the present ages of A and B is 40 years.
According to question:
3x + 5x = 40
8x = 40
x = 5
Age of B = 5x
= 5 × 5 = 25 years
Hence, the age of B is 25 years.