How Does Temperature Change Affect Pressure in a Piston-Cylinder System?

[pleasehelpme6]

Warm air is contained in a piston-cylinder assembly cools slowly from volume of 0.003 m^3 to 0.002 m^3. During the process a spring exerts a force that varies linearly from an initial value of 900 N to final value of 0. Patm = 100 kPa and the area of the piston face is 0.018 m^2.

Or,

V1 = 0.003 m^3
V2 = 0.002 m^3

F1 = 900 N
F2 = 0

Patm = 100 kPa

I'm not exactly sure where to start here. Can someone help me figure out what formula to use?

 

[Delphi51]

PV = nRT applies to the air in the piston.
F = kx applies to the spring.
What is the question?