Determine the number of moles of air present in 1. 35 L at 750 torr and 17. 0°C. Ideal Gas Law formula: PV = nRT(R = 62. 396 L•torr/mol•K) Which equation should you use? P equals StartFraction n R T over V EndFraction. N equals StartFraction R T over P V EndFraction. N equals StartFraction P V over R T EndFraction.