What is the average Points For when there are Points Against more than 780, and Points smaller than 0?
CREATE TABLE "standings" (
  "club" text,
  "wins" real,
  "losses" real,
  "points_for" real,
  "points_against" real,
  "percentage" real,
  "points" real
);
SELECT AVG("points_for") FROM "standings" WHERE "points_against">780 AND "points"<0;