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 choice from the following answers:
A) 20
B) 98
C) 66
D) 54
E) 12
Let 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%   20nswer: 20
<result>A</result>
If the selling price of 50 articles is equal to the cost price of 40 articles, then the loss or gain percent is?