by selling 15 pencils for a rupee a man loses 25 % . how many for a rupee should he sell in order to gain 25 % ?
"75 % - - - 15 125 % - - - ? 75 / 125 * 15 = 9 answer : b"
multiply(divide(const_1, multiply(add(const_100, 25), divide(const_1, subtract(const_100, 25)))), 15)