Answer:
-2 m/s²
Step-by-step explanation:
Acceleration is the rate of change of velocity:
a = Δv / Δt
In other words, it's the slope of the line on a velocity-time graph. The line at t=3 also goes through the points (2, 4) and (4, 0).
a = (4 m/s − 0 m/s) / (2 s − 4 s)
a = -2 m/s²