I have a question with a horizontal cylinder with a piston attached to a spring inside the cylinder. air is then let into the cylinder and the spring contracts increasing the volume. the diameter of the piston is given (10cm), the spring force is given (80KN/m), the initial volume is given (1L) and the initial pressure is 150kPa. the final volume and temperature is given as well, (1.5L) and (80*C). the question asks to find the final pressure and mass after the air has been let into the cylinder. I know that F=kx F=P/a PV=mRT and Pv=RT, But i cant figure out how to manipulate these equations to solve for the pressure or the mass.