The ratio of Vimals age and Arunas age is 3 : 5 and the sum of their ages is 80 years. The ratio of their ages after 10 years will be:

A. 2 : 3
B. 3 : 2
C. 1: 2
D. 3 : 5
Answer: A

Explanation:  

Let their ages be 3x and 5x years.
Then,3x + 5x = 8O so x = 1O.
Ratio of their ages after 10 years = (3x+ 10) : (5x+ 10)
                                                  = 40 : 60
                                                  = 2 : 3