a shop keeper marked 30 % above the cost price and offered 20 % discount then find it ' s net profit ?
"net profit = 30 - 20 + ( 30 * ( - 25 ) / 100 ) = 2.5 % answer is b"
subtract(subtract(add(const_100, 30), divide(multiply(add(const_100, 30), 20), const_100)), const_100)