A Toyota Corolla costs $18,700 and has average highway fuel economy of 36 miles per gallon (mpg). A Toyota Prius costs $23,700 and offers average highway fuel economy of 50 mpg. 

a. Assuming gas costs $2.75 per gallon, generate total cost equations as a function of miles driven for each of these cars. Identify the fixed and variable costs.

b. How many miles do you have to drive before the two cars have the same total cost?

c. You plan on holding on to your next car for 100,000 miles. You estimate that you can sell a used Corolla with 100,000 miles for $4,400; a used Prius with 100,000 miles is worth $7,800. If money is the only thing that matters to you, should you buy the Corolla or the Prius?