Liquid water at 250 kPa and 20oC is heated in a chamber by mixing with superheated steam

Question:

Liquid water at 250 kPa and 20oC is heated in a chamber by mixing with superheated steam at 250 kPa and 350oC. Cold water enters the chamber at a rate of 2 kg/s. If the mixture leaves the chamber at 55oC, determine
(a) The mass flow rate of superheated steam.
(b) The entropy generation rate during mixing?