When do I use "was" and when do I use "were"

Question

Do I use was or were in this sentence?

Bonnie, along with her associates, was invited to the gathering.

Answer 1

The trick here is the use of the comma. Here, the two commas are used to provide additional, but not essential, information. Bonnie WAS.

Answer 2

They were. (Plural)

She was. (Singular)

"Bonnie and her associates" are "they" so you would say were:

Bonnie and her associates were invited to the gathering.

However, in your sentence, the associates are not part of the subject, so you would say:

Bonnie, along with her associates, was invited to the gathering.