From the given data, calculate the enthalpy of combustion of cyclopropane at $298 \: K$. The enthalpy of formation of $CO_2(g), H_2O(l)$ and propene(g) are $-393.5, -285.8$ and $20.42 \: kJ/mol$ respectively. The enthalpy of isomerisation of cyclopropane to propene is $-33 \: kJ/mol$