a shopkeeper allows 10% discount on his goods to make 20% profit, if he sold a watch for Rs.10170 with 13% vat, by what percent is the discount to be increased to make only 12% profit

16% of MP

Step-by-step explanation:

Key concepts to learn :

Discount is always applied on marked price.

Profit = SP - CP

VAT is applied on Selling Price

SP = 10170/113 x 100 = 9000

If profit is 20% then :

CP = 9000/120 x 100 = 7500

MP = 9000/90 x 100 = 10000

For 12% profit, SP = 7500 x 112/100 = 8400

=> SP = 8400/10000 x 100 = 84% of MP

=> Discount = 16% of MP