Answer:
The stopping car has negative acceleration.
Step-by-step explanation:
We know acceleration is the rate of change of velocity. That is
Acceleration(a) = ( Final velocity - Initial velocity )/ Time taken.
Here Final velocity = 0 km/h( car stops) and initial velocity = 30 km/h
So acceleration = (0-30)/time = -30/ time
Time is always positive , so -30/time is negative, so the stopping car has negative acceleration.