The rate of change in an equation can usually be found with what number is being multiplied with X or whatever variable you have. So in this equation it shows that a ride's cost goes up the more miles (X) you need to go, the number being multiplied would be 2.50 so for each mile you need to go it increases by $2.50. There is a small note though, since you need to subtract 3 from whatever your X is, that means that there is a minimum of 3 miles you need to go for an uber ride to be valid. Regardless, the rate does not change, just has a different minimum.
So the rate of change would be $2.50 per mile
