Chemistry(Please help)
posted by Hannah .
The vapor pressure of diethyl ether is 463.57 mm Hg at 25 degrees celsius. How many grams of aspirin C9H8O4, a non volatile nonelectrolyte (mw=180.1g/mol), must be added to 216.7g of ether to reduce the vapor pressure to 453.74 mm Hg.
Ether=74.12g/mol
so I did 463.57  453.74 = 7.600
Then I found moles of ether to be 4.0313.
I do not understand the next step to find Xether.

You had better subtract again. 7.600 is not right.
You need the mole fraction of ether. You get that by
pether = Xether*Po ether
You know partial pressure of ether to be 453.74 (that's what you want it to be)
You know Po ether to be 463.57. Solve for Xether. 
I subtracted again and got 9.83.
So do I set it up like this
453.74= Xether * 463.57 
Disregard question.