One type of ultrasonic humidifier uses a vibrating piezoelectric crystal actuator to produce tiny water droplets in

Question:

One type of ultrasonic humidifier uses a vibrating piezoelectric crystal actuator to produce tiny water droplets in the air. If 20 lbm/min of air at 70 8F enters the humidifier with a relative humidity of 20% and leaves at the same temperature with a relative humidity of 60%, how much water is being added each hour?