user: Question: Who was the opponent with the record of 15-21-6?
Columns: ['Game', 'January', 'Opponent', 'Score', 'Record']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [37.0, 1.0, '@ Boston Bruins', '2 - 1', '11-20-6']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Record" = '15-21-6';