Correct Answer - Option 1 : 17 years

Given

5 years ago, ages of mohit and rohan = 5 : 6

7 years after, ages of mohit and rohan = 11 : 12

Calculation:

Present age of mohit = 5x + 5 .

Present age of rohan = 6x + 5

After 7 years in future, their ages will be 5x + 5 + 7 and 6x + 5 + 7 respectively

According to question,

⇒ (5x + 12)/(6x + 12) = 11/12

⇒ 60x + 144 = 66x + 132

⇒ 6x = 12

⇒ x = 2

So, the present age of rohan = 6x + 5 = 12 + 5 = 17 years

∴ The required answer is 17 years