A car rents for $45 per day plus 21 cents per mile. You are on a daily budget of $66. What mileage will allow you to stay within your budget?

Your budget = $66.

Car rental (for the car) = $45

Car rental (for each mile) = $0.21.

To work out the price you can afford, do 66 - 45 = $21.

Now do $21 : $0.21 to find out the number of miles you can drive.

$21 : $0.21 = 100 miles.

You can drive for 100 miles.