a merchant marks his goods up by 50 % and then offers a discount of 20 % on the marked price . what % profit does the merchant make after the discount ?
"let the price be 100 . the price becomes 150 after a 50 % markup . now a discount of 20 % on 150 . profit = 120 - 100 20 % answer a"
subtract(subtract(add(50, const_100), divide(multiply(add(50, const_100), 20), const_100)), const_100)