Independent and dependent variables

Question

Sam rented a car for a week, drove 580 miles, and paid $327. Eliza rented a car for a week, drove 305 miles, and paid $217. Both friends mentioned that there was a rental fee for the car and an additional rate per mile that the car was driven. Explain which is the independent and the dependent variable.

Answer 1

The total cost depends on the mileage driven.  Thus, cost is the dependent variable and mileage is the independent variable.