I just need part B (delta U) solved for thank you

A gas is contained in a vertical piston-cylinder assembly by a piston with a face area of 70 in2 and weight of 100 lbf. The atmosphere exerts a pressure of 14.7 lbf/in2 on top of the piston. A paddle wheel transfers 3 Btu of energy to the gas during a process in which the elevation of the piston increases slowly by 4 ft. The piston and cylinder are poor thermal conductors, and friction between the piston and cylinder can be neglected. Determine the work done by the gas on the piston, in Btu, and the change in internal energy of the gas, in Btu. Step 1 Your Answer Correct Answer X Your answer is incorrect. Determine the expansion work done by the gas on the piston, in Btu. Wexp = 2.653 Btu Hint Solution Assistance Used Step 2 X Your answer is incorrect. Determine the change in internal energy of the gas, in Btu. AU = i 0.85 Btu e Textbook and Media Hint Save for Later Attempts: 1 of 4 used Submit