Since here velocity is not given , we assume the speed as velocity .
u=72 km/h=72*5/18 m/s=20 m/s.
Since final velocity is not given , we assume it to be 0.
v=0 , t=10 s.
=-20/10 m/s² = -2 m/s².
The bus is accelerating at the rate of -2 m/s².
or it is decelerating at the rate of 2 m/s².