How much percent above the cost price should a shopkeeper mark his goods so that after allowing a discount of 20% on the marked price, he gains 12%?

Let the CP be Rs. 100 and MP be Rs. x

Gain % after discount = 12%

Gain = 12% of 100 = Rs. 12

Then, SP of the article = CP + Gain = Rs. (100 + 12) = Rs. 112

Discount % = 20%

Discount = 20% of Marked Price = Rs.20/100 * x = Rs. 20x/100 = Rs. x/5

As per question-

Marked Price - Discount = SP

=> x - x/5 = 112

=> (5x - x)/5 = 112

=> 4x/5 = 112

=> x = 112 * 5/4 = Rs. 140

Marked Price = Rs. 140

Amount marked above the CP = MP - CP = Rs. (140 - 100) = Rs. 40

**Therefore, % amount marked above the CP = Amount increased/CP * 100 = 40/100 * 100 = 40%**