Inventory system with multiple quantity values

I have built an inventory system and I am working on adding a feature to it that will allow groups of parts to be reserved. I need a way that I can display the quantity of the item, how many are reserved and the final available total.

The application is for internal use only and different tiers of employees will be using it. Some employees will only see the quantity, some will see the available items and those that will be reserving/ordering items will need to see all of the quantities.

Each item has a table row with a quantity column. I had thought of displaying the item quantities as a simple X(Y) where X is the quantity and (Y) is the reserved amount. But I think it is too ambiguous. A user could see 5(2) and think a total of 5 items, with 2 reserved and 3 available. Another user could see 2 reserved for a total of 7 items, with 5 available. For this reason I would like to have the application do the math and not have the users do any of the thinking.

I have also thought of adding an extra column for the available quantity, but that would mean my table would have empty spaces where the majority of items do not have anything reserved. I would also like to avoid adding more columns as it is already a large table.

The most recent idea I have looked into is displaying all values in a single quantity column and using the superscript tag (<sup>) with background colours and a divider, such as |, \, /. Here is what I had in mind.

This displays the quantity, the reserved amount raised, with a background colour and the - in front of the number and the available items a bit off to the side. So 22 items in total, 4 reserved and 18 available.

I do not know if this is sufficiently self-explanatory. Is there a way I can make it more so? Or is there a better way to display all of these values in a single column?