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 answer.
A) 10
B) 30
C) 20
D) 60
E) 50
C   20   Let C.P. of each article be $ 1.   Then, C.P. of 50 articles = $50;   S.P. of 50 articles = $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: