user: Question: How many times were Duke the opponents?
Columns: ['Game', 'Date', 'Opponent', 'Result', 'Tar Heels points', 'Opponents', 'Record']
Types: ['real', 'text', 'text', 'text', 'real', 'real', 'text']
Sample row: [1.0, 'Sept. 6', 'Furman', 'Win', 35.0, 13.0, '1-0']
SQL:

assistant: SELECT COUNT("Opponents") FROM "Table" WHERE "Opponent" = 'Duke';