1 to 2 , Isobaric process
2 to 3, Isochoric process
3 to 1, Isothermal process

Using work under isobaric, isochoric and isothermal processes respectively:

$$\begin{gathered} \mathrm{W} = {\mathrm{W}}_{1\to 2} + {\mathrm{W}}_{2\to 3} + {\mathrm{W}}_{3\to 1} \\ \mathrm{W} = \left(\right(-\mathrm{P}({\mathrm{V}}_2 - {\mathrm{V}}_1) + 0 + (-{\mathrm{P}}_1{\mathrm{V}}_1(\ln \frac{{\mathrm{V}}_2}{{\mathrm{V}}_1}\left)\right) \\ =\left(\right(-1(40 - 20) + 0 + (-1 \times 20 (\ln \frac{20}{40}\left)\right) \\ =620 \mathrm{J} \end{gathered}$$