Not sure if my title is accurate of my problem; I struggled to find the right description.

I need a formula to be able to calculate a total of different rates depending on the item total. By this I mean:

For one item, I charge $75.
For multiple items, I charge $75 for the first and $25 for each additional.

One item would total $75, 3 items would total $125, 5 items would total $175 and so on.

Does anyone have any suggestions of how I can calculate this with an excel formula? I am using Excel 2010.

Let me know if you need any additional information.

Thanks for your help.

Laura