user: Question: What is the average goal difference with 51 goals scored against and less than 17 losses?
Columns: ['Position', 'Club', 'Played', 'Points', 'Wins', 'Draws', 'Losses', 'Goals for', 'Goals against', 'Goal Difference']
Types: ['real', 'text', 'real', 'text', 'real', 'real', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'UE Lleida', 38.0, '57+19', 23.0, 11.0, 4.0, 56.0, 20.0, 36.0]
SQL:

assistant: SELECT AVG("Goal Difference") FROM "Table" WHERE "Goals against" = 51.0 AND "Losses" < 17.0;