A cross flow heat exchanger with a mix of benzene and toluene entering at $30$ degrees C and exiting at $80$ degrees C flowing at $2\mathrm{.}7$ kg$/$s$.$ It has an area of $20$m squared. What should the air temperature in and out be and what should the flow of air in to achieve $80$ degrees C on the waters exit? Assume one fluid is mixed and one fluid is not mixed.