If the question is asking for acceleration,
To find acceleration, we have to find the change in velocity over the change in time
In this case, the change of velocity is -30 km/hr and the change in time is 5 seconds
We must convert the units of sec to hours to solve this question
5 sec * 1 min/60 seconds * 1 hour/60 min = .00138889 hours
acceleration = change in velocity / change in time = -30 km/hr / .00138889 hours = -21599.999 km/hr^2 = ~-21600 km/hr^2