it takes joey the postman 1 hours to run a 1 mile long route every day . he delivers packages and then returns to the post office along the same path . if the average speed of the round trip is 5 mile / hour , what is the speed with which joey returns ?
"let his speed for one half of the journey be 3 miles an hour let the other half be x miles an hour now , avg speed = 5 mile an hour 2 * 1 * x / 1 + x = 5 2 x = 5 x + 5 = > 3 x = 5 = 5 / 3 = 1.67 a"
divide(1, subtract(divide(multiply(const_2, 1), 5), 1))