Are theses sentences simple or compound sentences?

Alex's younger brother, Cameron, and two other friends also became interested in the benefit.

I think simple because it is just one independent clause.

They would charge people for a dinner and hold the auction at the dinner.

I think simple.

the first one is simple and the second one is compound

What about the group continued planning the benefit, but not many people would buy the $25 tickets for the dinner.

Compound?

The second sentence is not compound. It has one subject and two verbs. It, too, is a simple sentence.

The sentence about the benefit is compound.

Actually, both of the sentences you provided are compound sentences. Let me explain how to identify simple and compound sentences.

A simple sentence consists of one independent clause, which means it has one subject and one predicate (verb). It conveys a complete thought. For example, "Alex's younger brother became interested in the benefit."

On the other hand, a compound sentence consists of two or more independent clauses joined together by coordinating conjunctions like "and," "but," or "or." Each independent clause in a compound sentence can stand alone as a complete sentence. For instance, "Alex's younger brother and two other friends became interested in the benefit."

Applying this understanding to your examples, let's break them down:

1. "Alex's younger brother, Cameron, and two other friends also became interested in the benefit."

This sentence has one subject, "Alex's younger brother, Cameron, and two other friends," and one predicate, "also became interested in the benefit." It contains multiple elements joined by commas ("Cameron" and "two other friends") and conveys a complete thought. Thus, it is a compound sentence.

2. "They would charge people for a dinner and hold the auction at the dinner."

Similarly, this sentence consists of one subject, "they," and one predicate, "would charge people for a dinner and hold the auction at the dinner." It also contains multiple elements joined by the coordinating conjunction "and." Therefore, it is another compound sentence.

In summary, both of the given sentences are compound sentences since they contain more than one independent clause.