The ages of A and B are in the ratio 5 : 7. Four years from now the ratio of their ages will be 3 : 4. The present age of B is
Let the ages of A and B be 5x and 7x
By cross multiplication
⇒ 4(5x + 4) = 3(7x + 4)
⇒ 21x - 20x = 16 - 12
⇒ x = 4
Age of B = 7x = 28 years
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