$A \rightarrow B :$ 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
$W _{\text {Isobaric }}= P \Delta V = nR \Delta T$
$W _{\text {Isochoric }}=0$
$W _{1}= nRT \ln \left(\frac{2 V }{ V }\right)= nRT \ln 2$
$W _{2}= nR \left(\frac{ T }{2}- T \right)=- nR \frac{ T }{2}$
$W _{3}=0$
$\Rightarrow W _{ net }= W _{1}+ W _{2}+ W _{3}$
$W _{ net }= nRT \left(\ln 2-\frac{1}{2}\right)$


(Take $R$ = $8.3\ J/mol-K$ and $ln\ 2$ = $0.69$)