If only one press is used, it takes the older press twice as long to print an edition as it takes the newer press. If the two presses together can print an edition in 3 hr, how long will it take each press alone to print an edition?
Let x denote the older press's publishing rate (in editions/hr). Then the newer press's publishing rate is 2x (ed/hr). If the two presses work together for 3 hours, they produce 1 edition. 3(x + 2x) = 1 9x = 1 x = 1/9 So the older press does 1/9 of an edition per hour when working by itself, and the newer press does 2/9 of an edition in an hour. So the older press would take 9 hr to do 9/9 of an edition, and the newer press would take half that time, of 4.5 hr.
