A stream of air (stream 1) at 60°F, 1 atm, 30% relative humidity is mixed adiabatically with a stream of air (stream 2) at 90°F, 1 atm, 80% relative humidity. A single stream (stream 3) exits the mixing chamber at temperature T3 and 1 atm. Assume steady state and ignore kinetic and potential energy effects.

Letting r denote the ratio of dry air mass flow rates m˙a1/m˙a2 determine T3, in °F, for r = 0.1

T3 = ______ F