A man sits in a bosun's chair that dangles from a massless rope, which runs over a massless, frictionless pulley attached to the ceiling and back down to the man's hand. The combined mass of the man and chair is 90.0 kg. Ok, I found a solution that had T=Mchair*a + Fnormal + Mchair*g. How did they know to separate the man and the chair when the problem only gives you a mass for the combined mass of the man and the chair? Then the problem asks for the weight exerted by the ceiling onto the whole system. Why is this answer not just all of the weights added together?