Need help in calculating Small business Inventory

I am using Excel for a small business Inventory Count. I have Couple of Columns, but i would love to set formulas for only 2.
I have an "Inventory on hand" column, a "Plus" column, and a "Minus" Column. I would love to set a formula to automatically detect if there is a value added in the "Minus" column and if so it would subtract the "Minus" from the "Inventory on Hand" and put the new Value into a new cell in the "Inventory on Hand" Column, And Same for the Plus. To Add "Plus" to "Inventory on Hand" and add the new value to a new cell in the "Inventory on Hand" Column.

Any Help would be appreciated.

I added an attachment that shows how it looks.