Using the formula for finding distance we can determine Usian Bolts average speed or rate when he broke the world record in 2009 in the 100m. So there is also instantaneous speed. How to calculate average speed.
V d t where v is the velocity d is the distance and t is the time so you can read it as Speed Distance Time.
We can try to measure it by using a very short span of time the shorter the better. For the first part of the trip you know that 30 miles 15 mph t so you know that t 2 hours. What is his average speed for the whole trip. Total distance 50 3 60 2 270.