It is desired to use methane in an adiabatic recovery boiler in which it is intended to obtain superheated steam at 120 C from 6 kg/s of water at 20 C and 1 atm. The fuel used enters at 25 C and 1 atm, with a mass flow rate of 3 kg/s. The coefficient of excess air used is 1.153, entering the air at a temperature of 177 C and a pressure of 1 atm. Calculate: a) Combustion gas outlet temperature b) Assuming that there is no generation of steam, obtain the temperature of the combustion gases.