Answer:
The rate of speed is 5 miles per hour.
Explanation:
Choose two lines of data as two ordered pairs:
(0, 20) and (4, 40)
The rate of speed is the same as the slope of the line that passes through those two points.
slope = (difference in y)/(difference in x)
slope = (40 - 20)/(4 - 0) = 20/4 = 5
The slope is 5, so the speed is 5 mph
Answer: The rate of speed is 5 miles per hour.