a. 30 - 15 = 15
----------------------- = 15 miles per hour
2-1 = 1
b. 60 - 15 = 45
----------------------- = 15 miles per hour
4 - 1 = 3
c. 60 - 30 = 30
-------------------- = 15 miles per hour
4 - 2 = 2
in conclusion they are all the same cause they have the same slope
