Problem: by selling 12 pencils for a rupee a man loses 20 % . how many for a rupee should he sell in order to gain 20 % ?
Rationale: "80 % - - - 12 120 % - - - ? 80 / 120 * 12 = 8 answer : a"
annotated_formula: multiply(divide(const_1, multiply(add(const_100, 20), divide(const_1, subtract(const_100, 20)))), 12)