In a combustion chamber, propane (C3H8) is burned at a rate of 5 kg/h with air enters

Question:

In a combustion chamber, propane (C3H8) is burned at a rate of 5 kg/h with air enters at a rate of 140 kg/h. Determine
(a) The percent of excess air used, if the reactants enter at 25oC, also determine
(b) The adiabatic flame temperature (Taf). Assume the products to be perfect gas mixture with cp= 1.005 kJ/kg-K.