A thermodynamic process is shown fig. The pressures and volumes corresponding to some points in the figure are
$$\begin{gathered} {\mathrm{P}}_{\mathrm{A}}=3×{10}^4\mathrm{Pa},{\mathrm{V}}_{\mathrm{A}}=2×{10}^{−3}{\mathrm{m}}^3 \\ {\mathrm{P}}_{\mathrm{B}}=8×{10}^4\mathrm{Pa},{\mathrm{V}}_{\mathrm{D}}=5×{10}^{−3}{\mathrm{m}}^3 \end{gathered}$$
In process AB, 600 J of eat is added to the system and in process BC 200 J of heat is added to the system. The change in internal snergy of the system in process AC
would be