$\gamma=1+\frac{2}{f}$
$\gamma =1+\frac{2}{14}=\frac{8}{7}$
$W =\frac{n R \Delta T}{\gamma-1}=-582$
As ${W}\,<\,0$. Work is done on the gas.


$A \rightarrow B :$ Isothermal expansion at temperature $T$ so that the volume is doubled from $V _{1}$ to $V _{2}=2 V _{1}$ and pressure changes from $P _{1}$ to $P _{2}$
$B \rightarrow C :$ Isobaric compression at pressure $P _{2}$ to initial volume $V _{1}$
$C \rightarrow A$ : Isochoric change leading to change of pressure from $P _{2}$ to $P _{1}$
Total workdone in the complete cycle $ABCA$ is
