Position and Displacement

Pick an origin and a positive direction. The position $x$ is where the object is, measured from the origin; its sign gives the side.

The displacement is final minus initial position:

$$\Delta x = x_{\text{final}} - x_{\text{initial}}$$

From x = $5\ \mathrm{m}$ to x = $-2\ \mathrm{m}$: the displacement is $-7\ \mathrm{m}$.

Distance is the length of the path, never negative. Out $40\ \mathrm{m}$ and back $40\ \mathrm{m}$ is a distance of $80\ \mathrm{m}$ but a displacement of 0.