Answer:
A compound predicate is two or more simple predicates joined by a conjunction that indicate actions by the same subject. A conjunction is a word used to join two separate thoughts together in a sentence (such as while, and, as, etc.), to create a compound predicate.
For example: Alex found 5 cents on the sidewalk while he was walking his dog.
The predicates are found 5 cents on the sidewalk and he was was walking his dog. The conjunction is while.
It has the same subject for both verbs.