The C.P of 20 pens is equal to the S.P of 12 pens. Find his gain % or loss%?	Select the correct option:
A) 10%  B) 20%  C) 30%  D) 40%  E) 50%
20 CP = 12 SP   20 --- 8 CPgain   100 --- ? =&gt; 40%   Answer: 40%
<result>D</result>
The C.P of 20 pens is equal to the S.P of 12 pens. Find his gain % or loss%?