the salary of a worker is first increased by 40 % and afterwards reduced by 40 % . what is the net change in the worker ' s salary ?
"let x be the original salary . the final salary is 0.6 ( 1.4 x ) = 0.84 x the answer is c ."
subtract(const_100, subtract(add(40, const_100), divide(multiply(add(40, const_100), 40), const_100)))