Ineed to know the answer to 6 and 7

If f(x)= 3x+6 which of the following is the inverse of f(x)

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?

Would greatly appreciate these 3 answers