Subhash purchased a tape recorder at 9 / 10 th of its selling price and sold it at 8% more than its selling prices. His gain is?

Let the S.P. be Rs. P
Then, C.P. paid by subhash = Rs. (9 x P)/10
S.P. received by subhash = (108% of Rs. P) = Rs. (27 x P) / 25
∴ Gain = Rs.(27 x P) / 25 - (9 x P) / 10 = Rs. (9 x P) / 50
Hence, Gain% = (9P / 50) x (10P / 9) x 100 % = 20%