Problem: after decreasing 25 % in the price of an article costs rs . 1500 . find the actual cost of an article ?
Rationale: "cp * ( 75 / 100 ) = 1500 cp = 20 * 100 = > cp = 2000 answer : d"
annotated_formula: divide(1500, subtract(const_1, divide(25, const_100)))