In this context, the situation involves a cost structure where Superior Segway Tours charges a flat fee plus a variable rate based on time. The one-time fee of $40 is a fixed cost, while the $35 charge per hour is the variable cost.
In this case, the slope represents the rate of change of the total cost with respect to time. Since the charge per hour is $35, the slope in this situation, which indicates how much the total cost increases for each additional hour of the tour, is:
35
So the correct answer is 35.