David is driving to a concert and needs to pay for parking. There is an automatic fee of $9 just to enter the parking lot, and when he leaves the lot, he will have to pay an additional $3 for every hour he had his car in the lot. How much total money would David have to pay for parking if he left his car in the lot for 2 hours? How much would David have to pay if he left his car in the lot for t hours?​