user: Question: Which Attendance has a Result of W 51-21?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'September 7, 1980', 'Detroit Lions', 'L 41-20', 64892.0]
SQL:

assistant: SELECT "Attendance" FROM "Table" WHERE "Result" = 'W 51-21';