Two boxes are at rest on a smooth, horizontal surface. The boxes are in contact with one another. If box 1 is pushed with a force of magnitude F = 12.00 N, the contact force between the boxes is 8.50 N; if, instead, box 2 is pushed with the force F, the contact force is 12.00 N - 8.50 N = 3.50 N. In either case, the boxes move together with an acceleration of 1.70 m/s2. What is the mass of
(a) Box 1
(b) Box 2?