10 yr before, the ratio of ages of A and B was 13 : 17. After 17 yr from now, the ratio of their ages will be 10 : 11. The present age of B is

Let the ages of A and B 10 yr before were 13k yr and 17k yr, respectively.
Then, present age of A = 13k + 10
and present age of B = 17k + 10
According to the question,
∵ (13k + 10 + 17) / (17k + 10 + 17) = 10/11
⇒ (13k + 27) / (17k + 27) = 10/11
⇒ 143k + 297 = 170k + 270
⇒ 27k = 27
∴ k = 1
Hence, present age of B = 17 x 1 + 10 = 27 yr