user: Question: What is the number of attendance values for ties having an opponent of middlesbrough and result of 3-1?
Columns: ['Date', 'Opponent', 'Venue', 'Result', 'Attendance']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['17 August 1996', 'Aston Villa', 'H', '2-1', 26861.0]
SQL:

assistant: SELECT COUNT("Attendance") FROM "Table" WHERE "Opponent" = 'middlesbrough' AND "Result" = '3-1';