user: Question: What is the average of goals against, where overall goals are more than 35 and the goal difference is 20?
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, 'CP Mérida', 38.0, '56+18', 23.0, 10.0, 5.0, 55.0, 19.0, 36.0]
SQL:

assistant: SELECT AVG("Goals against") FROM "Table" WHERE "Goals for" > 35.0 AND "Goal Difference" = 20.0;