PROBLEM II $[12$pt$]$

A piston$-$cylinder device initially contains $0\mathrm{.}50$ kg af airgat $2\mathrm{.}8$ MPa and $320C.$ The gas first expanded isothermally to a pressure of $0\mathrm{.}5$ MPa $,$ and then compressed polytropically with $n-1\mathrm{.}4$ back to the initial pressure, and finally compressed at constant pressure to the initial state. Calculate the boundary work, in kJ$,$ for each thermodynamic process and find the net work for the cycle.