user: Question: How many opponents were there at the game with 64,087 people in attendance?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Kickoff [a ]', 'Game site', 'TV', 'Attendance', 'Record']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Week', 'Date', 'Opponent', 'Result', 'Kickoff [a ]', 'Game site', 'TV', 'Attendance', 'Record']
SQL:

assistant: SELECT COUNT("Opponent") FROM "Table" WHERE "Attendance" = '64,087';