The problem: An engine puts an ideal monatomic gas through a clockwise rectangular cycle on a PV diagram with horizontal and vertical sides. The lower left point has a pressure of 1 atm and a volume of 1m^3 and the upper right point has pressure and volume three times greater. Calculate the efficiency of a Carnot engine operating between the highest and lowest temperatures. Solution (so far): I know that for a Carnot engine e=1-T_c/T_h, but without being given the temperature differences I'm not exactly sure how you'd begin. I calculated the efficiency of the engine itself to be 22.2%, the work done in the cycle to be 4.04x10^7 J, and the heat absorbed in the cycle to be 434 kcal; if any of those quantities can be related to T_c/T_h. The answer comes to be 88.9%. Thanks in advance for any help.