Problem: the cost price of an article is 64 % of the marked price . calculate the gain percent after allowing a discount of 15 % ?
Rationale: "let marked price = rs . 100 . then , c . p . = rs . 64 , s . p . = rs . 85 gain % = 21 / 64 * 100 = 32.8 % . answer : a"
annotated_formula: multiply(subtract(divide(subtract(const_100, 15), 64), const_1), const_100)