Sushil was thrice as old as Snehal 6 years back. Sushil will be times as old as Snehal 6 years hence. How old is Snehal today?

A. 18 years
B. 12 years
C. 24 years
D. 15 years
Answer: B

Explanation:  

Let Snehals age 6 years back = x.
Then, Sushils age 6 years back = 3x.
(5/3) x (X + 6 + 6) = (3X + 6 + 6) hence 5(x+ 12) = 3(3x+ 12) so x=6.
Snehal today = (x+ 6) years = 12 years.