Air in a tank is at 300 kPa, 400 K with a volume of 2 m3. A

Question:

Air in a tank is at 300 kPa, 400 K with a volume of 2 m3. A valve on the tank is opened to let some air escape to the ambient to a final pressure inside of 200 kPa. At the same time the tank is heated so the air remaining has a constant temperature. What is the mass average value of the s leaving assuming this is an internally reversible process?