automatically calculate price

I sell tires and I'm having a hard time setting up a spreadsheet that will do what I need done.

The cost of 1 tire of X brand my formula is easy. It is =SUM(F2+25). F2 is my cost and 25 is my profit.

If I sell two tires I want the formula to add my cost + 79.00 + 2.00 for each 1.00 increase in my cost in a separate cell. Can anyone help me with this formula?

Hopefully I will soon be able to change the cost in my spreadsheet and the price for both 1 and 2 tires will automatically calculate themselves. Any help is appreciated.

If I sell two tires I want the formula to add my cost + 79.00 + 2.00 for each 1.00 increase in my cost in a separate cell. Can anyone help me with this formula?

Can you clarify this a bit more? Your cost goes up as you increase the amount of tires? So lets say you have 1 tire the cost is $50....when you sell two its now what per for the cost?

Thanks for your offer of help. Once I got the brain back working I worked the formulas out.