Let's break it down. The rule, per Purdue OWL, is that you should not put a comma between the two verbs or verb phrases in a compound predicate. "John" is the subject of the sentence. "Ate a slice ...

It's the two parts of a sentence. The subject is the noun. The predicate is the verb. I have an example of a compound subject. A blond, dark-eyed woman named Nomeda and her mother, Virginia ...

And in those few simple words ... t put a comma before a conjunction in a compound predicate, which means two or more verbs are shared by the same subject: “Bob took a shower and walked the ...