Notice that the velocity is negative when t > 4.5.
When velocity is negative, Stevie moves back towards his starting position.
Total distance is the area under a speed graph. Speed is the absolute value of velocity.
A speed graph is the absolute value of a velocity graph...
Area under a speed graph = total distance.
Area under a velocity graph = displacement.
Distance from starting point is known as 'displacement.'
Displacement is the area under a velocity graph.
Acceleration is slope on a velocity graph.
See hint in part (d).