1. 75g sample of a gaseous mixture contains .51 mole fraction propane. The remainder is butane. What are the masses of propane and butane? 2. X = mol A / mol total 3. The attempt at a solution P = mol propane B = mol butane I tried doing .49P + .49B = X mol propane and .51P + .51B = Y mol butane however that doesn't seem to be solvable. I'm not quite sure how I should manipulate the 75 g of solution.