GMAT Math Practice Test #1

Answer B Assume original price = 100
Sale price after first discount of 10% = 100- 10% = 90
The second discount is given on the net sale price after first discount.
Sale price after second discount of 20% = 90- 20% = 72
Sale price after first discount of 40% = 72- 40% = 72-28.8 =43.2
Total discount on 100 =100- 43.2 = 56.8 = 56.8%

Key takeaway: The discount is given on the sale price. If there are series of discounts, the discount is worked out on previously discounted price and not on original sale price.