Limit form submission to 20

I have 2 event options A & B that can be selected.Dates for A & B are the same (date field w range/ 9/11/2023 & 9/12/2023)Times for A are 9:00pm & 9:30pm (choice field - House Tour Times)Times for B are 9:00pm & 9:20pm (choice field - Trolley Tour Times)

Only 20 people are allowed on each tour. I want to assign a limit so only 20 people can register per tour.

I set up a calculation field to set the limit and input the following: =Event+Date+House Tour. Limit Specific Qty 20

This works for Event A but won’t’ register for Event B since the time is a separate field and if I add another calculation field for Event B all the calculations fail.

Please help!