Final answer:
The cost y of renting a truck is expressed by the linear equation y = 20 + 0.35x, where x represents the number of driving miles and y represents the total cost.
Step-by-step explanation:
The cost y of renting a truck can be represented as a linear equation in terms of the driving miles x. Given the rate of $0.35 per mile and an initial fee of $20, the equation relating the total rental cost to the driving miles is:
y = 20 + 0.35x
Here, the independent variable is x (the number of driving miles), and the dependent variable is y (the total cost of the rental). The initial fee of $20 represents the y-intercept, which is the cost when x is zero, while the rate of $0.35 per mile is the slope of the equation, representing the additional cost per mile driven.