A thermodynamical process is shown in  with PA= 3 X 104 Pa; VA = 2 X 10-3 m3; PB = 8 x 104 N/m2; VD = 5 x 10-3 m3.In the processes AB and BC, 600 J and 200 J of heat is added to the system respectively. The change in internal energy of the system in process AC would be: