by selling 15 pencils for a rupee a man loses 60 % . how many for a rupee should he sell in order to gain 60 % ?
"40 % - - - 15 160 % - - - ? 40 / 160 * 15 = 3.75 answer : d"
multiply(divide(const_1, multiply(add(const_100, 60), divide(const_1, subtract(const_100, 60)))), 15)