Heat is allowed to flow from the heat source of a heat engine at 425 k to a cold sink at 313 k. what is the efficiency of the heat engine? the answer should have three significant figures. %

I assume here that the engine operates following a Carnot cycle, which achieves the maximum possible efficiency. 

Under this assumption, the efficiency of the engine (so, the efficiency of the Carnot cycle) is given by

where
is the cold temperature
is the hot temperature

For the engine in our problem, the cold temperature is 313 K while the hot temperature is 425 K, so the effiency of the engine is