by selling 16 pens for a rupee a woman loses 5 % . how many for a rupee should he sell in order to gain 18 % ?
d 95 % - - - 16 118 % - - - ? 95 / 118 * 16 = 13
inverse(add(divide(divide(const_100, subtract(const_100, 5)), 16), divide(multiply(divide(divide(const_100, subtract(const_100, 5)), 16), 18), const_100)))