By selling 50 meters of dress. I gain the selling price of 15 meters. Find the gain percent?  Choose the correct choice from the following:
A) 52 6/9% B) 45 8/7% C) 42 6/7% D) 12 8/3% E) 56 6/7%
42 6/7%   SP = 42 6/7%P + g   50 SP = 50 42 6/7%P + 15 SP   35 SP = 50 42 6/7%P   35 --- 15 42 6/7%P gain   100 --- ? =&gt; 42 6/7%
<result>C</result>
By selling 50 meters of dress. I gain the selling price of 15 meters. Find the gain percent?