Is there a function for something like this.

Okay I have an attached excel file, I am doing inventory and cant use an inventory control software of ne kind as it would take far to long to enter in the name of all the material. I have Columns: Material; add; remove; total on hand.

I am trying to make the total amount to be reflected by either add and remove columns, the only problem is it possible to make the add and remove just add to each other. Say i am adding none but removing 5, i do not want to have to change removing 5 back to zero next time i go to change it, the only columns that are to change the total are the add and remove. Its somewhat confusing to explain