user: Question: What is the average number of points for an Offenhauser L4 engine with a Trevis chassis?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1950.0, 'I R C', 'Maserati', 'Maserati L4', 0.0]
SQL:

assistant: SELECT AVG("Points") FROM "Table" WHERE "Engine" = 'Offenhauser L4' AND "Chassis" = 'Trevis';