If the cost price of 12 pens is equal to the selling price of 10 pens, the gain percent is:
Choose the correct choice:
A) 80% B) 90% C) 20% D) 40% E) 10%
Explanation:   Let C.P. of each pen be Re. 1.   Then, C.P. of 10 pens = Rs. 10; S.P. of 10 pens = Rs. 12.   Gain % = 2/10 * 100= 
<gadget id="calculator">2/10 * 100</gadget>
<output>20</output>
20%   Answer:20%
<result>C</result>
If the cost price of 12 pens is equal to the selling price of 10 pens, the gain percent is: