$$ Methane is burned with air in a continuous steady$-$state combustion reactor to yield a mixture of carbon monoxide, carbon dioxide, and water. The feed to the reactor contains $12$ mole$\%$ CH$4,25\%$ O$2,$ and $63\%$ N$2.$ The percentage conversion of methane is $80\mathrm{.}0\%,$ and the gas leaving the reactor contains $4$ mol CO$2/$mol CO$.$ Please write down the reactions, draw the flowchart and write everything on it$.$ Carry out a degree$-$of$-$freedom analysis on the process. Then calcute the molar composition of the product stream.