if im given the initial and final air temperatures, and the gas compression ratio, how do i find the efficiency (in %) of the cycle??? here's the question.

Consider a Diesel cycle that starts with air temperature 300 K. The air may be treated as an ideal gas. If the temperature at the very end of isobaric expansion is 950 K, and gas compression ratio is 21, what is the efficiency ( in %) of this cycle? Give your answer with one decimal point accuracy