$A \rightarrow B :$ 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