7 years ago, the ages (in years) of A and B were in the ratio 4 : 5 and 7 years hence, that will be in the ratio 6 : 7. The present age of B is:

42

Ratio of age of A and B (7 years ago) = 4 : 5

Ratio of age of A and B (7 years hence) = 6 : 7

ATQ,

⇒ \(\frac{4R + 14}{5R + 14}\) = \(\frac{6}{7}\)

⇒ 28R + 98 = 30R + 84

⇒ 2R = 14

⇒ 1R = 7

So,

Ages of A and B (7 years ago) = 4 x 7, 5 x 7 = 28, 35

Present ages = (28 + 7), (35 + 7) = 35, 42