Time is the independent variable and cost is the dependent variable because cost of renting depends on the number of hours rented.
Explanation:
The answer for the first box is independent variable because the independent variable is a constant value and is usually of x-coordinate.
The cost is the dependent variable because the y-value depends on the change in x-value. It is given that the cost varies as the time increases. Hence, cost is a dependent variable.
Also, the costing of renting depends on the number of hours rented, since cost is a dependent variable and the the cost raises if the time rented increases.
Thus, Time is the independent variable and cost is the dependent variable because cost of renting depends on the number of hours rented.