Abus 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 .