A stream of outdoor air is mixed with a stream of return air in an air conditioning system that operates at 101 kPa pressure. The flow rate of outdoor air is 3 kg/s, and its condition is 30 degrees Celsius Tdb and 23 degrees Celsius Twb. The flow rate of return air is 2.5 kg/s and its condition is 15 degrees Celsius Twb and 60% RH. Determine (a) the enthalpy of the mixture, (b) humidity ratio of the mixture, (c) the dry bulb temperature of the mixture, and (d) the dry bulb temperature by the weighted average of the dry bulb temperatures of the entering streams.