average speed = total distance / total time

(a) To find the average speed in kilometers per hour:

total distance = 35 km

total time = 6 hours and 20 minutes = 6.33 hours (since 1 hour = 60 minutes)

average speed = 35 km / 6.33 hours = 5.53 km/h

Therefore, the average speed in kilometers per hour is 5.53 km/h.

(b) To find the average speed in centimeters per second, we need to convert kilometers per hour to centimeters per second. We can use the following conversion factors:

1 km = 1000 m

1 m = 100 cm

1 hour = 3600 seconds

So, 1 km/h = (1000 m / 1 km) * (100 cm / 1 m) / (3600 seconds / 1 hour) = 27.78 cm/s

Using this conversion factor, we can convert the average speed in kilometers per hour to centimeters per second:

average speed = 5.53 km/h * 27.78 cm/s = 153.27 cm/s

Therefore, the average speed in centimeters per second is 153.27 cm/s