Generating a list of items not selected in another table

Hi everyone

I’m looking for a formula for formatting a column that will let me have all items which aren’t selected in another table auto-fill.

Basically, I have table A with about 200 items.
I then have table B, with some of those 200 items selected.
I now want table C to have all items from table A that aren’t selected in table B.

Any ideas? I’m still learning my way around the formulas!