How do I combine two separate formulas into one cell?

Example:

Column name is "Total Enrollment"

Formula 1 (Currently already in the column): =COUNTIF({Class ID}, [Class ID]@row)

The formula has a Reference sheet.

Formula 2 (which I want to add in the same column): =SUM([Total Enrollment]@row - [Waitlisted]@row)

(Basically I want the cell to exclude the Waitlisted lines from the Reference sheet).

I get an #INSEPARABLE error when I try to do it like =COUNTIF({Class ID}, [Class ID]@row) + " " + =SUM([Total Enrollment]@row - [Waitlisted]@row)

Am I doing this incorrectly, or is it actually not possible to combine the formulas? Or is there another way to exclude something in my Total Enrollment column without having to use a second formula?

Thanks!