As a front passed the temperature changed steadily over 7 hours all together it changed -21 degrees what was the change in temperature per hour for 7 hours

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?