If the selling price of 50 articles is equal to the cost price of 40 articles, then the loss or gain percent is: Choose the correct option:
A) 45%  B) 23%  C) 20%  D) 60%  E) 56%
C   C.P. of each article be Re. 1.   Then, C.P. of 50 articles = Rs. 50;   S.P. of 50 articles = Rs. 40.   Loss % = 10/50 * 100= 
<gadget id="calculator">10/50 * 100</gadget>
<output>20</output>
20%
<result>C</result>
If the selling price of 50 articles is equal to the cost price of 40 articles, then the loss or gain percent is: