Calculator with inputs & outputs in same cells

Hi.

This one is hard to explain but I'd imagine maybe not too hard to do.

In the attached file, I want to allow the user to write either the sodium or salt percentage for each ingredient 1-5, depending on what is listed on the package, and for the "grams" columns to take into account those numbers and calculate an equal number of grams of each ingredient necessary to achieve the salt percentage put in at the top. BUT!, I'd like the user to also be able to adjust the amount of grams of any particular ingredient such where say they want to add 50g of salt, then the MSG and ingts 1-5 would all be adjusted to equal amounts of the remainder, and so on.

I hope this makes sense.

Thanks!