Refrigerant 134a at a flow rate of 0.5 lb/s enters a heat exchanger operating at steady state as a saturated liquid at 0 0F and exits at 20 0F. A separate air stream enters at 120 0F and exits at 77 0F. The heat exchanger is insulated such that there is no heat transfer to the surroundings. Modeling the air as an ideal gas, determine the mass flow rate of the air in lb/s.