The ratio of the ages of A and B is 3 : 5. After 9 years, their ages will be in the ratio 3 : 4. What is the current age of B?

मान लीजिए आयु 3x, 5x है। (3x + 9) / (5x + 9) = 3/4 => 12x + 36 = 15x + 27 => 3x = 9 => x = 3। B की आयु = 5 * 3 = 15 वर्ष।