-

Problem 11-65

Raoult's Law

P_sol = P_methanol χ _methanol + P_propanol χ _propanol

Knowing that:
χ _methanol = 1 - χ _propanol

you need to subtitute:
χ _methanol     by   1 - χ _propanol   in equation 1
and search for  χ _propanol
since you already have all the other informations.