A bus slows down uniformly from 75.0 km/h to 0 km/h in 21 s. How far does it travel before stopping?

1 hour = 3,600 seconds

1 km = 1,000 meters

75 km/hour = (75,000/3,600) m/s = 20-5/6 m/s

The average speed of the bus while it slows down is

(1/2) (20-5/6 + 0) = 10-5/12 m/s.

Traveling at an average of 10-5/12 m/s for 21 seconds,

the bus covers

(10-5/12) x (21) = 218.75 meters.