The way I started this problem was drawing 3 force diagrams. For the 1.0kg mass, there were two forces, weight and tension. The second mass, m (2.6kg), had 5 forces; normal, weight, 2 tensions, and kinetic friction in the negative x direction. The last mass, also had 2 forces, tension and weight. I think it would be relatively easy to find acceleration if it wasn't for the tension of the first mass. I'm not sure how to go about solving for that. Any ideas?