Answer:
A bake sale or a car wash makes a great fundraiser.
Explanation:
A compound subject is the formation of a new single, longer noun phrase by combining two or more individual noun phrases. This new longer phrase becomes the single subject in the sentence.
The two given sentences are "A bake sale makes a great fundraiser and "A car wash makes a great fundraiser". And by joining the two subjects of the sentences by the coordinating conjunction "or", we can make a new compound subject "a bake sale or a car wash".
Thus, the final sentence with a compound subject using coordinating conjunction is
<u>"A bake sale or a car wash makes a great fundraiser".
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