Given that a combined power plant efficient performance is attributed to heat transfer. Consider a combined gas power plant having net power output of $540$MW$,$ with network output per unit mass of gas $($W$)588\mathrm{.}6$KJ$/$Kg$,$ and required rate of heat input in the combustion chamber $($Qm$)-740,215$kw$.(1)$ Determine that the plant thermal efficiency is above $60\%,($ii$)$ Calculate the plant mass flow rate