5kg of steam contained within a piston-cylinder assembly undergoes an expansion from state 1 to state 2. during this process the specific internal energy changes from u1=2709.9 kj/kg to u2=2659.6 kj/kg. during the process there is a heat transfer to the steam of magnitude 80 kj. also, the paddlewheel transfers 18.5 kj of energy to the steam by work. determine the energy transfer by work from the steam to the piston, in kj.