McDonald put in 14 points and hauled down six rebounds. Johnson provided 12 points and nine boards.
Reggie Bullock put in 10 points for the Tar Heels (7-2), who jumped out to a 34-4 lead and never looked back.
The Buccaneers (2-5) managed to get 18 points from Rashawn Rembert but it wasn't enough to prevent the one-sided loss.
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