not sure if this is the correct formula for finding percentage used by each driver.

Attach a sample workbook (not a picture or pasted copy). Make sure there is just enough data to demonstrate your need. Include a BEFORE sheet and an AFTER sheet in the workbook if needed to show the process you're trying to complete or automate. Make sure your desired results are shown, mock them up manually if necessary.

Remember to desensitize the data.

Click on GO ADVANCED and then scroll down to Manage Attachments to open the upload window.

How much of this question is Excel and how much is basic algebra? It is not clear to me exactly what you want to do here, but it feels like a basic "percent of" problem like you would have learned way back in basic algebra. I might suggest you start with an algebra refresher like this: https://www.purplemath.com/modules/percntof.htm

It seems that these kinds of problems are as easy or as difficult as identifying the desired quantities in the statement "a is what% of b" which translates into a=x*b. Your example of C3/N3 appears to be "(Day shift 1's January fuel usage) is what % of (day shift 1's December fuel usage)". If that is the statement you are trying to describe with your formula, then that is the correct formula. That does not appear to be correct to me, as your statement in the OP seems more like "(Day shift 1's January fuel usage) is what % of (a total fuel usage)". I'm not sure which total you are wanting to compare to, but it should be as easy as identifying the correct total and referencing that cell.

Does that help at all?