Question

The forces acting on a box in opposite direction are F1=200 N and F2=150N

Find the resultant force acting on the box ? then represent it by a vector? 

Answer 1

Let's take the direction to the right as the positive direction. Let's suppose that the force $F_1$acts in the positive direction to the right and the force $F_2$ - in the opposite direction to the left. Then, the resultant (net) force can be found as follows:

$$F_{net}=F_1-F_2=200\ N-150\ N=50\ N.$$

The sign plus means that the resultant force directed to the right.