What kind of formula do i use to find out the cheapest rate to use for the car rental?

Mr. Smith wants to rent a Suv to go from home to a conference in Seattle, he expects to do 350 miles in total during this journey
There are 3 rental companies:
Hertzy Rental-Fixed rate of $58 dollars with no mileage charge
Alabo Rental-Charge $.35 cents per mile
Nifty Rental-Charge a fixed rate of $28 plus $.15 cents per mile

charge for x miles:

Hertz: 58
Alabo: .35x
Nifty: 28 + .15x

so, for 350 miles, you get

Hertz: 58.00
Alabo: .35(350) = 122.50
Nifty: 28 + .15(350) = 80.50

I guess it's easy now to tell which is cheapest for a 350-mile rental.

To find the cheapest rate for car rental, you will need to compare the rates offered by each rental company based on the total mileage you expect to drive.

For Hertzy Rental, the rate is a fixed $58 with no mileage charge. Therefore, regardless of how many miles you drive, the rate remains the same.

For Alabo Rental, they charge $0.35 cents per mile. To calculate the cost for 350 miles, you multiply the mileage (350 miles) by the mileage rate ($0.35 cents per mile):
Cost for Alabo Rental = 350 miles * $0.35 per mile

For Nifty Rental, they have a fixed rate of $28 plus $0.15 cents per mile. To calculate the cost for 350 miles, you multiply the mileage (350 miles) by the mileage rate ($0.15 cents per mile) and add the fixed rate ($28):
Cost for Nifty Rental = (350 miles * $0.15 per mile) + $28

Now, compare and calculate the cost for each rental company:

Cost for Hertzy Rental: $58 (no mileage charge)
Cost for Alabo Rental: 350 miles * $0.35 per mile
Cost for Nifty Rental: (350 miles * $0.15 per mile) + $28

After calculating these costs, you will be able to determine which rental company offers the cheapest rate for your journey. Choose the rental company with the lowest cost.