I need to rent a car for my forthcoming trip. Rent-N-Go charges $21 per day plus 15 cents per mile. Super Rentals Plus charges $18.50 per day plus 21 cents per mile. I plan to do a good deal of driving during all three days of my trip, and I need to know which company will give me a better deal overall. How many miles would I have to drive to make the cost of renting a car from Rent-N-Go the same as the cost of renting a car from Super Rentals Plus? Explain how I should decide which rental car company to use.