Hi, I have the 2003 version of Excel and was wondering if anyone knew how to create a formula that adds figures into several cells at once?

Basically, I am trying to create a sheet that calculates stock levels and profit/loss each day. The confusion comes in where I have a special offer, as it takes away stock in several of the other rows.

For example, say I have Item 1, 2, 3 and then the offer. The offer has one of all these items. If someone buys all of the items through the offer, I want it to take away stock from each item's stock levels.

Sales Stock left
Item 1 3 7-2
Item 2 4 6-2
Item 3 6 4-2
Offer 2 N/A

The -2s are what I want the formula to do as I have sold 2 of the offer. How can I do this?

Hope this makes some sense!

Thanks, Rob

EDIT: oh dear, it seems to have messed up my table. I have colour coded it- each colour corresponds to a different column