What is the highest Goal Difference when the goals against were less than 76, and the position larger than 5, and a Played larger than 30?
CREATE TABLE "group_i" (
  "position" real,
  "club" text,
  "played" real,
  "points" real,
  "wins" real,
  "draws" real,
  "losses" real,
  "goals_for" real,
  "goals_against" real,
  "goal_difference" real
);
SELECT MAX("goal_difference") FROM "group_i" WHERE "goals_against"<76 AND "position">5 AND "played">30;