robert ' s salary was decreased by 40 % and subsequently increased by 40 % . how much percentage does he lose ?
"let original salary be $ 100 salary after decreasing 40 % = 100 - 100 x 40 / 100 = $ 60 salary after increasing 40 % on $ 60 = 60 + 60 x 40 / 100 = $ 84 percentage of loss = 100 - 84 = 16 % answer : a"
multiply(divide(subtract(multiply(const_100, const_100), multiply(subtract(const_100, 40), add(const_100, 40))), multiply(const_100, const_100)), const_100)