A paddle-wheel is employed in a rigid container for stirring a hot fluid to be cooled. The internal energy of the hot fluid is \(1000 \mathrm{~kJ}\). During the cooling process, the fluid losses \(600 \mathrm{~kJ}\) of heat. For this process, the work done by the paddle-wheel on the fluid is \(100 \mathrm{~kJ}\). Calculate the final internal energy of the fluid.