What is the average goals for that has +40 as the goals difference, with points 1 greater than 55?
CREATE TABLE "final_table" (
  "position" real,
  "team" text,
  "played" real,
  "drawn" real,
  "lost" real,
  "goals_for" real,
  "goals_against" real,
  "goal_difference" text,
  "points_1" real
);
SELECT AVG("goals_for") FROM "final_table" WHERE "goal_difference"='+40' AND "points_1">55;