working alone , printers x , y , and z can do a certain printing job , consisting of a large number of pages , in 12 , 40 , and 50 hours , respectively . what is the ratio of the time it takes printer x to do the job , working alone at its rate , to the time it takes printers y and z to do the job , working together at their individual rates ?
"p 1 takes 12 hrs rate for p 2 p 3 together = 1 / 40 + 1 / 50 = 9 / 200 therefore they take 200 / 9 ratio = 200 / 9 = d"
divide(12, divide(const_1, add(divide(const_1, 40), divide(const_1, 50))))