By selling 99 pens, a trader gains the cost of 66 pens. Find his gain percentage?
Select the correct option
A) 66 1/3%  B) 66 7/3%  C) 66 1/8%  D) 66 2/3%  E) 66 1/5%
Let the CP of each pen be Rs. 1.   CP of 99 pens = Rs. 99   Profit = Cost of 33 pens   = Rs. 33   Profit% = 66/99 * 100   = 66 2/3%   Answer: 66 2/3%
<result>D</result>
By selling 99 pens, a trader gains the cost of 66 pens. Find his gain percentage?