Refrigerant 134a expands in a piston-cylinder assembly from 180 lbf/in.2 and 140°F to 30 lbf/in.2 The mass of refrigerant is 0.5 lb. During the process, heat transfer to the refrigerant from its surroundings is 1.2 Btu while the work done by the refrigerant is 4.32 Btu. Determine the final temperature of the refrigerant, in °F. Kinetic and potential energy effects are negligible.