Festival Inventory Check-Out, Check-In

I'm working on an inventory db for a festival. I'm tracking supplies and equipment use, check-out and check-in. I have an "Inventory" table with items and set quantities. I would like to track when items are checked out and subsequently returned also reflected this "available" count in my "Inventory" view.  My question is whether I need two tables, "CheckOut" and "CheckIn" and somehow join them together.  Or, do I have one table say "History" that logs each transaction with a "Status" field, "Out" & "In".  In which case how do I create an expression to calculate the "available" count in my "Inventory" view?