You have the liquid compositions, then you must to find
y1+y2+y3=1(vapor phase) AND x1+x2+x3=1(liquid phase), yi=ki*xi, yuo have xi. you must find Ki. a tmperature of equilibrium, the pressure is the total. and comprobe the sum=1. you have the pressure and the euilibrium temperatura,like sum(ki*xi)=1 yuo heve yi in the vapour phase