A tank open to the atmosphere initially contains 2 lb of liquid water initially at 80°F and 0.4 lb of ice initially at 32°F. All of the ice melts as the tank contents attain equilibrium. If no significant heat transfer occurs between the tank contents and their surroundings, determine the final equilibrium temperature, in °F. For water, the specific enthalpy change for a phase change from solid to liquid at 32°F and 1 atm is 144 Btu/lb.