Total vapor pressure of mixture = P(benzene) + P(toluene) Ptotal = X(benzene)(Pbenzene pure) + X(toluene)(Ptoluene pure) X = mole fraction Ptotal = (7.97 /(7.97 + 5.90))380 + (5.90/(7.97 + 5.90)) 130 Ptotal = 0.575(380) + 0.425(130) = 274 torr Solution Total vapor pressure of mixture = P(benzene) + P(toluene) Ptotal = X(benzene)(Pbenzene pure) + X(toluene)(Ptoluene pure) X = mole fraction Ptotal = (7.97 /(7.97 + 5.90))380 + (5.90/(7.97 + 5.90)) 130 Ptotal = 0.575(380) + 0.425(130) = 274 torr.