Air at 1 atm, 15oC, and 60 percent relative humidity is first heated to 20oC in a

Question:

Air at 1 atm, 15oC, and 60 percent relative humidity is first heated to 20oC in a heating section and then humidified by introducing water vapor. The air leaves the humidifying section at 25oC and 65 percent relative humidity. Determine
(a) The amount of steam added to the air
(b) The amount of heat transfer to the air in the heating section.