Problem: by selling 20 pencils for a rupee a man loses 60 % . how many for a rupee should he sell in order to gain 60 % ?
Rationale: "40 % - - - 20 160 % - - - ? 40 / 160 * 20 = 5 answer : e"
annotated_formula: multiply(divide(const_1, multiply(add(const_100, 60), divide(const_1, subtract(const_100, 60)))), 20)