For part A, I thought of 2 ways to approach the problem. Is my analysis correct in that deltaU from point A to C equals the negated deltaU from point C to A? My second method was just calculating the difference in temperature and using the formula deltaU = 3/2 * n * R * deltaT . These two methods don’t match however. So I guess my question is, first, is my first method right? And then, is there a reason the second method doesn’t match other than the question wasn’t designed consistently? Thanks for your help.