Are you saying that you will NEVER have a record/row that has BOTH a number typed in for previews AND a number typed in for performances? It's either one or the other?
If so, then I would recommend a completely different setup that would make things much simpler for you and would also allow you to generate some advanced reporting from your numbers, such as pivot tables.
Instead of having 2 columns — one for previews and one for performances — I would recommend having just 1 column for "number of shows".
Then, create a single-select field for "type of show" with the options of "preview" and "performance".
That way, each one of your lines is tagged as either a preview or performance, and there is only one number field that you need to look at.
This opens the door to all sorts of advanced automations, advanced functionality, and advanced reporting down the line! And it makes it much easier to do simple things too, like filtering/grouping/sorting/coloring.
Hope this helps! If you’d like to hire an expert Airtable consultant to help you with anything Airtable-related, please feel free to contact me through my website: Airtable consultant — ScottWorld
Does this look right?

IF(
Previews,
Previews,
Performances
) *
{Production Seats (from Linked table)}
If both a 'Preview' and 'Performance' value exists then it'll default to using 'Preview'. Let mw know if this is a problem and I'll see what I can do!
Link to base
Are you saying that you will NEVER have a record/row that has BOTH a number typed in for previews AND a number typed in for performances? It's either one or the other?
If so, then I would recommend a completely different setup that would make things much simpler for you and would also allow you to generate some advanced reporting from your numbers, such as pivot tables.
Instead of having 2 columns — one for previews and one for performances — I would recommend having just 1 column for "number of shows".
Then, create a single-select field for "type of show" with the options of "preview" and "performance".
That way, each one of your lines is tagged as either a preview or performance, and there is only one number field that you need to look at.
This opens the door to all sorts of advanced automations, advanced functionality, and advanced reporting down the line! And it makes it much easier to do simple things too, like filtering/grouping/sorting/coloring.
Hope this helps! If you’d like to hire an expert Airtable consultant to help you with anything Airtable-related, please feel free to contact me through my website: Airtable consultant — ScottWorld
You make a great point, and I think this may be the way forward. I've been copying info from a sheet sent to me for these two columns, so keeping it consistent with the sheet I got sent to me was more straightforward. (since importing the data doesn't work with the linked fields, etc in Airtable vs the columns in the sheet with its mapping capabilities)
Thanks, Scott!
Does this look right?

IF(
Previews,
Previews,
Performances
) *
{Production Seats (from Linked table)}
If both a 'Preview' and 'Performance' value exists then it'll default to using 'Preview'. Let mw know if this is a problem and I'll see what I can do!
Link to base
Hi Adam!
This is what I needed. I am not that new to Airtable, but I am a bit of a novice when I need minor scripting/formulas, and I was getting hung up on using two IF's in my attempts. This worked beautifully. Thank you for your time!
ckanayag