18. Devin drove up a hill. After he drove 4 minutes, he was at an elevation of 620 feet. After he
drove 12 minutes he was 1,580 feet high.
a. Should the x-values represent minutes or feet? Why?
b. Calculate the rate of change in this situation. What method did you use and why?
c. If he continues to climb at this rate, how much elevation will he gain in the next 15 minutes?