Thermodynamics: Steady Flow Energy Balance (1st Law), Mixing Chamber

Solution to the following problem (Thermodynamics: An Engineering Approach, CBK, 8th Edition, 5-71) Liquid water at 300 kPa and 20 C is heated in a chamber by mixing it with a superheated steam at 300 kPa and 300 C. Cold water enters the chamber at a rate of 1.8 kg/s. If the mixture leaves the mixing chamber at 60 C, determine the mass flow rate of the superheated steam required.