A 35-ft3 insulated, 90-lbm rigid steel tank contains air at 75 lbf/in 2, and both tank and air are at 70 F. The tank is connected to a line flowing air at 300 lbf/in 2, 70 F. The valve is opened, allowing air to flow into the tank until the pressure reaches 250 lbf/in 2 and is then closed. Assume the air and tank are always at the same temperature and find the final temperature.