Given the revenue and cost functions R(x) =26x-0.3x^2 and C(x) = 3x+11, where x is the daily production, find the rate of change of revenue with respect to time when x = 15 units and dx/dt = 8 units per day.

Solve the problem by making up an equation. a man could arrive on time for an appointment if he drove the car at 40 mph; however, since he left the house 15 minutes late, he drove the car at 50 mph and arrive 3 minutes early for the appointment. how far from his house was his appointment?