looks like just PV=nRT problem.. do they give you this information?
(water vapor pressure at 90.0 degrees C is 70.1 kPa)
what does the exact question read?
It looks like the vapor pressure from the water would be deducted from the total pressure of the water vapor if that information is given to you.. I'm trying to remember why or how to use that information, I am not in Chemistry right now, doing Physics and Calc..