A 559.0 mL cylinder containing C5H12 at a pressure of 304.0 torr is connected by a valve to 610.0 mL cylinder containing CO2 at 532.0 torr pressure. Calculate the partial pressure (atm) of CO2 when the valve is opened.

I would use PV = nRT and solve for n = number of moles C5H12 in the 559 mL cylinder. Do the same for n of CO2 in the 610 mL container. Add the moles C5H12 to moles CO2 and recalculate P from the sum of the volumes of each container. I note that no T is given but I would use a convenient one, say 100 (actually, 1 would work, too, and it would simplify the calculation a little).