a bus decreases its speed from 80kmh-1to 60kmh-1 in 5 sec find the acceleration

60,000 m/3600 s = 16.7 m/s

80,000 m/3600 s = 22.2 m/s

(16.7 - 22.2)m/s / 5 s = -1.11 m/s^2