Answer
The normal force on the table is $62N$.
Work Step by Step
The normal force $F_N$ acting on the table is balanced by the vertical forces from box 1 and box 2.
$$F_N=\sum F_{1, y}+\sum F_{2, y}$$
- For box 1, it is simply the weight of it $$\sum F_{1, y}=m_1g=55N$$
- For box 2, the weight of it is opposed by the tension of the rope, which is caused by the weight of box 3. In other words, $$\sum F_{2, y}=m_2g-T=m_2g-m_3g=35-28=7N$$
Therefore, $$F_N=55+7=62N$$
