Shilpa's gym membership includes a one-time fee of $20. She then pays a discounted fee of $5 for each visit. The function that shows her average cost after x visits is:

How many revolutions will a car wheel of diameter 28 in. make over a period of half an hour if the car is traveling at 60 mi/hr? the final answer is supposedly 21,609 but i have no idea how to get that, show work : )