Ethane $($CH$)$ is burned with $200$ percent theoretical air during a combustion process.$/$Assuming complete combustion and a total pressure of $1$ atm. determine the air$-$fuel ratio $($AF$=$mar$/$muel$.($assuming the mass, C: $12$ kg$/$kmol$,$ H$2$: $2$ kg$/$kmol$,$ air: $29$ kg$/$kmol$,$ and air is composed of $20\mathrm{.}9\%$ oxygen and $78\mathrm{.}1\%$ nitrogen$)$