31m/s is the velocity of the object and in 6 seconds the object stops so its velocity is then 0 m/s. acceleration formula is a = Δv / Δt = (vf - vi)/(tf - ti) =(final velocity - initial velocity)/(final time - intial time) kinda like the slope formula right?
so subsitute the values (0 - 31)/(6 - 0) The answer should be negative as the velocity is decreasing
