Problem: a shopkeeper forced to sell at cost price , uses a 800 grams weight for a kilogram . what is his gain percent ?
Rationale: "shopkeeper sells 800 g instead of 1000 g . so , his gain = 1000 - 800 = 200 g . thus , % gain = 200 * 100 ) / 800 = 25 % . answer : option b"
annotated_formula: multiply(divide(add(multiply(const_2, const_100), divide(const_100, const_2)), 800), const_100)