Car rental agency charges a base rate plus a certain amount per day (d) and can be modeled using the expression 15+ 18d. What is the meaning of 18d in the expression? * 4 points
It is the base rate to rent a car.
It is the cost of renting a car for a day.
It is the total number of days a car can be rented.
It is the portion of the cost based on renting a car for d days.

It is the portion of the cost based on renting a car for d days

Step-by-step explanation:

Given:

Total cost = 15 + 18d

Total cost = fixed cost + variable cost

Fixed cost are cost that do not change.

Fixed cost = base rate = 15

Variable cost changes during production process. The variable cost in the above varies with the number of days (d)

Therefore, 18d is the portion of the cost based on renting a car for d days.

If you rent the car for 1 day

Total cost = 15 + 18d

= 15 + 18(1)

= 15 + 18

= 33