Answer
B
Work Step by Step
$[\dot{m}c_p(T_1-T_2)]_a=[\dot{m}c_p(T_2-T_1)]_w+\dot{Q}$
$\dot{m}_a=3\ kg/s,\ c_{p,a}=1.005\ kJ/kg.K,\ T_{1,a}=85°C,\ T_{2,a}=20°C$,
$\dot{m}_w=2\ kg/s,\ c_{p,w}=4.18\ kJ/kg.K,\ T_{1,w}=15°C,\ \dot{Q}=25\ kJ/s$
$T_{2,w}=35.45°C$
