The rental rate for a power washer has a one time fee of $60 plus $20 for each day of the rental. The graph shows the points representing the total cost of the rental. 150 (4,140) 125 Total Cost 100 (2,100) 75 50 25 1 2 3 Days Write an equation, in slope-intercept formly = mx + b) that models the total cost of the rental over time.