Data entry in one sheet modifying values in another sheet?

Hi everyone! I’m creating an inventory workbook. What I’d like to do is have one tab with our inventory counts, and another tab with data entry that will modify our inventory counts. For example I start my sheet with 5 blue shirts on tab A; tomorrow Katie comes in and asks for 2 blue shirts, which I will enter on tab B, which will then bring my blue shirt count in tab A down to 3. Is there a way to do this? I figure there must be, but having a hard time figuring it out and Googling it 😂 any tips? Thanks so much!!