For the best results in getting help in the Tableau Community Forums would be to attach a packaged workbook to the post with the question.
For just an idea of how to display the data, I would use SIZE possibly to display which of the products has more of the product mix. This will give a visual representation of how the total is being affected.
Hope this helps!
It sounds like you want to calculate the weighted average - which is the avg product price multiplied by the mix %. Have you tried something like this?
sum(avg product price * % mix)