4. We can describe the basic cost of renting a certain model of automobile by the equation C(x) 44x + 53, where x represents the whole number of
days that the car is rented, and C(x) is the cost to rent the car for that number
of days. Note that $44 is the cost per day, and $53 is the total of fixed fees that
do not depend on the number of days to rent the car. Ignore other taxes, etc.
When the renter selects a car with a GPS unit, the cost per day remains the
same, but the fixed fees increase by $14.