What if you were asked to solve R = A - B using the vectors in example I? When we subtract B from A, the only thing we need to do differently is change the sign of B. A negative sign in front of a vector means that its direction is changed by 180º degrees. Its direction is completely reversed. From North to South, East to West, 90º to 270º. After doing this we add the vectors using head-to-tail vector addition. See the example below:
R = A + B
R = A - B
Notice that the direction and magnitude completely change when adding and subtracting vectors. Thus adding and subtracting vectors does not give the same resultant vector.