too many cells have determining factors - how to use the ones with products

Working on a pricing calculator.
I am terribly sorry in advance for any confusion and my lack of proper terms.
I have a complex pricing calculator I have been working on and as soon as I feel like it is almost finished I get thrown a curve ball.
I need to calculate a set of cells but two cells have a determining factor. If L10 is used this needs to be apart of the final sum butttt if I9 is used then that cell needs to be a part of the final sum...
In the image where I9 (run charge) and I10 (other run charge) are connected to L10 - if L10 is used then the Sell price needs to use that cell if L9 is filled then that cell needs to be apart of the sell price calculation. Each cell in column I have formulas based on each of the cells in the table.
Thanks in advance
Sheet calc 2.PNG

There are instructions at the top of the page explaining how to attach your sample workbook.

A good sample workbook has just 10-20 rows of representative data that has been desensitised. It also has expected results mocked up, relevant cells highlighted and a few explanatory notes.

You attached a screenshot. I am asking you to attach the workbook, please.

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Thanks. Much easier than squinting at a screenshot! Having a look now.

Pleae update your forum profile as requested above.

Does this do what you want?

=MAX(I9:I10)/B12

I'm finding your explanation a bit hard to follow ...

OK, so either what I said before:

=MAX(I9:I10)/B12

or this:

=IF(I9="",I10,I9)/B12

Put one or other of my formulae into L10. This is the cell that determines which of the two values to use. In your final calculation, you use just L10: you don't need to decide again because the choice is already made in L10.

Please try it.

Let us know how you get on.

Essentially, where there is a choice of values, you deal with that choice in a helper cell like L10. Then, when it comes to final calculations, you simply use the helper cells.

If that takes care of your original question, please select Thread Tools from the menu link above and mark this thread as SOLVED.

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Super! Well done.