Question

I dont understand ..............

Answer 1

Take the upward and to-the-right directions to be positive (so down and to-the-left are negative).

The vertical forces acting on the object cancel, 6 N - 6 N = 0.

The horizontal forces exert a net force of 20 N - 3 N = 17 N. This net force is positive, so it points to the right. So the answer is A.