Can someone help me with this??

No matter how long they rent for, they have to pay at least 20. Any additional hour is 10. But since it says “part of an hour” that makes this really easy.
1) $30 (the first hour is 20, the second hour is 10 even though they didn’t use the full hour completely)
2)$30 (same situation as 1)
3)$40 (20+10+10)
4)$50 (20+10+10+10 even though that additional hour was only 1 min)
5) Below five hours and above three hours. If you’re spending $50 you rented it within at least four hours. I hope that makes sense