Physics problem regarding atwood's machine?

Question

please help me how to solve this problem
1. a box weighing 70 N rest on a table. a rope tied to the box runs vertically upward over a pulley and a weight is hung from the other end. determine the force that the table exerts on the box if the weight hanging on the other side of the pulley weighs a. 30 N b. 60 N c. 90 N

Answer 1

The pulley arrangement you describe is exactly like pulling straight up on the box. For example, 30 N leaves 40 N for the table to support. 90 N leaves 0 for the table to support

B