When 5 litres of a gas mixture of methane and propane is perfectly combusted at 0^oC and 1 atmosphere, 16 litres of oxygen at the same temperature and pressure is consumed, The amount of heat released from this combustion in kJ ($\Delta $H_comb. (CH₄) = 890 kJ mol^$-$1, $\Delta $H_comb. (C₃H₈) = 2220 kJ mol^$-$1) is