What is the noun in three students and their teachers are coming?

The noun in the sentence "Three students and their teachers are coming" is students.

Here's why:

* Students is the subject of the sentence. It's who is doing the action of "coming."

* Teachers is also a noun, but it's part of the noun phrase "their teachers," which modifies "students."

Let me know if you have any other questions about grammar! 😊