Adjustment in Excel file

I have an excel file in which product calculations are made. Now we would like in this file to also store and register stock or parts that we use. Please check out the attached printscreen. In AF-14 AF-32 the current stock is mentioned. In AG-14 AG-32 the ammounts which should be deducted are mentiond. And in AH-14 AH-32 the new stock ammount is mentioned. Now i would like on location F4 to be a button. When i press the button the amounts of AG-14 - AG-32 should be deducted from AF-14 AF-32 and should be mentioned in AH-14 AH-32. Then the file should be saved automatically.