A particle begins at the origin, travels along the X-axis to the...

Distance is the total path length covered by the particle.

The particle travels from $x = 0$ to $x = 20 \text{ m}$, covering a distance of $20 \text{ m}$.

It then travels from $x = 20 \text{ m}$ to $x = -20 \text{ m}$, covering a distance of $|-20 - 20| = 40 \text{ m}$.

Total distance $= 20 \text{ m} + 40 \text{ m} = 60 \text{ m}$.

Displacement is the change in position of the particle.

Initial position, $x_i = 0 \text{ m}$.

Final position, $x_f = -20 \text{ m}$.

Displacement $= x_f - x_i = -20 \text{ m} - 0 \text{ m} = -20 \text{ m}$.