A complex table, that would suit me massively should it work

Hi guys,

As this is my first post, I'll start with a quick introduction. My name's Boris, I am a Restaurant and Cafe Manager in a big company which has a lot of other sectors. I am a self taught excel amateur and am amazed by the functionality of this software.

Now on to my workbook. As I said we are a big company and the issue arises of transfer of stock, now my idea is to have a spread sheet, where daily stock transfers can be completed and it will produce a master one for finance to put through at the end of the month. It is much needed to be as simple as possible, but I got stuck. If you look into the file attached you will find it has a tab for every day. Where you select the product via a drop down menu, the department it is to be transfered to via drop down menu and then put in the ammount of items transfered or returned. But I am very confused as to how to make the Totals tab add up the quantity of all the products transfered to departments x, y, z etc, based on what was selected in the drop down menus in previous sheets ( I hope I'm making sense). And I also want to make it a sum of transfered items less the sum of returned items.

I hope you can give me a hand, and all is much appreciated.

Thanks,
Boris.