The ratio of the ages of A and B is 5:7. Eight years ago, the ratio was 7:13. What is B's current age?

मान लीजिए आयु 5x और 7x है। (5x-8)/(7x-8) = 7/13। 65x - 104 = 49x - 56 => 16x = 48 => x = 3. B की आयु = 7x = 7 * 3 = 21 वर्ष।