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Which sentence is written correctly?
His tips on finding buried treasure were believable, he had after all found buried treasure himself.
His tips on finding buried treasure were believable: He had, after all, found buried treasure himself.
His tips on finding buried treasure: were believable. He had, after all, found buried treasure himself.
The second sentence is written correctly:
His tips on finding buried treasure were believable: He had, after all, found buried treasure himself.