Table schema:
CREATE TABLE table_name_86 (points INTEGER, goals_for VARCHAR, goal_difference VARCHAR, club VARCHAR)

Question: what is the average points when the goal difference is less than 17, the club is getafe cf and the goals for is more than 30?
SQL: SELECT AVG(points) FROM table_name_86 WHERE goal_difference < 17 AND club = "getafe cf" AND goals_for > 30