Wet solids (F) containing 25% moisture are fed to a dryer at the rate of 1815kg/hr. The dried solids (P) have 2.0% moisture at the dryer exit (see figure below). Hot air (A) at 97C and with 30% relative humidity is available for use as drying medium. In order to regulate the rate of drying, part of the air leaving the dryer (N) is recycled back (R) and mixed with the hot air (A), so that the air stream entering the dryer (M) has a dew point of 69C. The exhaust air (E) is at 82 C and has 70% relative humidity. The whole process is carried out at the constant total pressure of 750 mmHg absolute. Calculate: a) The flow rate of the dried solids, in kg/h, b) The dryer duty, defined as kilograms of water evaporated in the dryer per hour, c) The molar ratio of recycle air to hot air (R/A), d) The volumetric flow rate of exhaust air (E) in m3/h