Physics question regarding forces?

Let's say there is a box that is not in motion. Person A pulls it to the right with X newtons and at an angle (so when broken into x and y components, the hypotenuse is given) and Person B trying to counteract the force pulls the box to the left but at a different angle. The problem asks what amount of force is required for Person B to counteract Person A. I know how to solve the problem, which is to find the hypotenuse of the force of Person B which goes to the left, but I don't know whether the answer is positive or negative. In one way it can be negative since the force of Person A must be counteracted by an opposing force, but then again it could be positive since the hypotenuse is always positive? Anyone that can tell if it should be positive or negative (or if it actually matters in the context of the problem) would be great, thanks.