Mahad marks an article 15% above the cost price of Rs. 540. What must be his discount percentage if he sells it at Rs. 496.80?

A. 18%
B. 21%
C. 20%
D. 19%
E. None of these
Explanation:
CP = Rs. 540, MP = 540 + 15% of 540 = Rs. 621
SP = Rs. 496.80, Discount = 621 – 496.80 = 124.20
Discount % = 124.2/621 * 100 = 20%