1 kilometer = 1000 meters.
Multiply total kilometers by 1000:
108 kilometers x 1000 = 108,000 meters.
1 hour = 3600 seconds.
Divide total meters by 3600:
108,000 / 3600 = 30 meters per second
Multiply 30 meters per second by 15 seconds:
30 x 15 = 450 meters in 15 seconds.