How much per cent above the cost price should a shopkeeper mark his goods so that after allowing a discount of 10% on the marked price, he gains 8%?

Let’s assume Cost Price of Product to be Rs.100.

Given he gains 8% on selling price would be

Selling Price = (100 + 8% of 100) = Rs.108

Discount = 10%

Let × be the marked price.

Market Price – Discount = Selling Price

x- (10% of x) = 108

× – x/10 = 108

9x/10 = 108

× = 120

Cost price is 100

Selling price is 108

Marked price is 120

So, Market Price is 20% above Cost Price.