The Bus Brain Teazer

Riddle: You're on a bus. 20 people get on at the first stop. At the next stop 45 people get on. At the 3rd stop 48 people get off. Then at the next stop 5 people get off and 9 get on. At the last stop 21 people get off 2 people are left. How is this possible? (Who's still on the bus)!?

Answer: This is possible because you and the bus driver are still on the bus! Source: https://riddles.com/3085

You're on a bus. 20 people get on at the first stop. At the next stop 45 people get on. At the 3rd stop 48 people get off. Then at the next stop 5 people get off and 9 get on. At the last stop 21 people get off 2 people are left. How is this possible? (Who's still on the bus)!? — The Bus Brain Teazer by GTFC12 Riddle