I think i can help! First, the rental fee is basically what you have to pay to get access to the item. It means that no matter how many hours you rent the item for, THE RENTAL FEE ALWAYS STAYS THE SAME. Next, The cost per hour is what you have to pay for every item you use the item. To figure out the cost per hour, all you need to do is multiply the cost per hour by the number of hours you are using the item. Lastly, the total cost if you are only using the item for one hour is the sum of the cost per hour and the rental fee. If you are using an item for more than an hour, like i said before, the rental fee always stays the same and you need to multiply the cost per hour by the number of hours you used the item. that’s all i can say my brains hurts now lol