By selling 50 meters of cloth. I gain the selling price of 15 meters. Find the gain percent?

A. 35%
B. 30%
C. 40%
D. 42 6/7%
Explanation:
SP = CP + g
50 SP = 50 CP + 15 SP
35 SP = 50 CP
35 — 15 CP gain
100 — ? => 42 6/7%