Operating a steady-state, a well insulated mixing chamber receives two input liquid streams of the same substance but with temperatures

Operating a steady-state, a well insulated mixing chamber receives two input liquid streams of the same substance but with temperatures T1and T2 and mass flow rates m1 and m2 respectively. The streams are mixed in the chamber, exiting as a single stream with T3 and m3. Assuming the substance is incompressible with constant specific heat C, that potential energy, kinetic energy, and pressure changes are negligible, obtain an expression for a) T3 in terms of T1, T2 and the ratio of the mass flow rates m1/m3. b) the rate of entropy production per unit mass exiting the chamber in terms of C, T1/T2 and m1/m3.