Which of the following represents the cost, in dollars, of renting a car for d days and driving m miles?

Rationale

45d + .25m represents the cost, in dollars, of renting a car for d days and driving m miles.

The formula breaks down the total cost into two components: a daily rental fee of $45 multiplied by the number of days (d), and a mileage fee of $0.25 multiplied by the miles driven (m), effectively capturing the total rental cost.

A (45+.25+ d+m) YOUR ANSWER

This option incorrectly adds fixed costs and variables without appropriate multiplication. It suggests a cost structure that does not account for the daily and mileage rates properly, leading to an inaccurate representation of the total cost.

B (45.25+ dm) YOUR ANSWER

This choice implies a combined cost of $45.25 but misrepresents the daily rental and mileage charges. The term "dm" suggests multiplying the number of days by the miles, which does not reflect the actual billing for daily rental and distance traveled separately.

C (45d +.25m) CORRECT

This is the correct answer, as it clearly expresses the total cost of renting the car. It accounts for $45 per day for d days and $0.25 per mile for m miles, thus accurately representing how the cost accumulates based on both time and distance.

D (45/d +25/m) YOUR ANSWER

This option incorrectly divides the daily rate and mileage rate by the respective variables. It implies a cost structure that diminishes with increased days or miles, which contradicts the principles of rental fees that increase with use.

Conclusion

The correct formula for calculating the cost of renting a car for d days and driving m miles is 45d + .25m, which accurately combines the daily rental fee and mileage charge. The other options misrepresent the relationship between days and miles with the costs incurred, leading to incorrect interpretations of the total rental expense. Understanding this formula is essential for budgeting travel expenses effectively.