7.92 meters, since its very clear that the particle at 4.67 seconds it was opposing the initial direction therefore you can say 11.3m - 3.387m and get your answer
Displacement = (distance between start and end points) in the direction of (direction from start to end point). Distance = (11.3-3.38)= 7.92 m. Direction = the negative 'x' direction.
