Multi Regression Model

Other than raw data, your post and sample file contain very little description of how you would like to perform this analysis. I am not an expert in this kind of data analysis, but the overall process I would expect to see is something like:

1) You mention regression, so the first task is to put together a regression model that will describe revenue in terms of the other parameters. I have no idea what that regression model should look like. In many ways, it is not really an Excel question, but more of a general data analysis question. What kind of regression model do you want to use? For example, ignoring everything but revenue and sales units, I could choose a simple model like R=m*U+b (R is revenue and U is sales units). Simple linear regression (Excel's LINEST() function: https://support.office.com/en-us/art...a-fa7abf772b6d ) will then give me m and b, and I have a simple regression model.
2) Once I have chosen a regression model and performed the regression, then I can work with the model to determine where it's maxima and minima are (calculus may come in handy here (something like this in 2D: https://www.mathsisfun.com/calculus/maxima-minima.html extended into multi-dimensions). Or maybe numerical methods (usually involving Excel's Solver utility) will be easier.

We are usually pretty good at the Excel programming side of these kinds of questions. If you can help us with the non-Excel part of choosing a regression model/equation, we should be able to help with the programming parts of the question.