you run a bus rental company that serves groups numbering between 20 and 80 people. if the group renting the bus has 20 people, they pay $80 per person. However, if they have 21 people, the price drops to $79 per person. For 22 people, the price is $78 per person. The price continues to dropping for each additional person in the group. Write an expression for the total amount you can charge a group of p people that rent one of you buses