user: Question: Tell me the average wins for class of 50cc and rank of 8th
Columns: ['Year', 'Class', 'Team', 'Points', 'Rank', 'Wins']
Types: ['real', 'text', 'text', 'real', 'text', 'real']
Sample row: [1969.0, '50cc', 'Tomos', 31.0, '6th', 0.0]
SQL:

assistant: SELECT AVG("Wins") FROM "Table" WHERE "Class" = '50cc' AND "Rank" = '8th';