So, work is force over a distance. Well, the mass of every infinitesimal piece of chain is simply 2dx kgs. What about the distance? If I read your problem correctly, you want to take the point 7 meters from the end and lift it so that that point is 15 meters above the ground which means that the bottom of the chain itself is 8 meters above the ground. Each infinitesimal unit of chain is therefore lifted 18-x units in the air. Integrate from 10 to 3 because the first 3 meters of chain have a different distance function. The answer is 161 I didn't take gravity into account. Again, I don't know the physics. Now, the first 3 meters of chain need to lifted as well. They have a different distance function. Theirs is 12+x. Integrate that function with 2 as a constant mass factor from 3 to 0 and get 81 for an answer. Add the two 242 is your answer without gravity as a factor.