Ratio of Ashoks age to Sandeeps age is 4 : 3. Ashok will be 26 years old after 6 years. How old is Sandeep now?

A. 12 years
B. 19 years
C. 15 years
D. 21 years
Answer: C

Explanation:  

Let their ages be 4x and 3x years.
Now 4x + 6 = 26 hence x = 5
 so Age of Sandeep = 3x = 15 years.