A and B are solutions of acid and water. The ratios of water and acid in A and B are 4 : 5 and 1 : 2 respectively. If x litres of A is mixed with y litres of B, then ratio of water and acid in the mixture becomes 8 : 13. What is x : y?

A. 5 : 6

B. 2 : 5

C. 3 : 4

D. 2 : 3

Answer: Option C

Solution (By Examveda Team)

In A, water = $$\frac{4}{9}$$
In B, water = $$\frac{1}{3}$$
In C, water = $$\frac{8}{{21}}$$

x : y = 3 : 4