Which Game has Points of 53, and an Opponent of @ minnesota north stars, and a December larger than 30?
CREATE TABLE "regular_season" (
  "game" real,
  "december" real,
  "opponent" text,
  "score" text,
  "record" text,
  "points" real
);
SELECT AVG("game") FROM "regular_season" WHERE "points"=53 AND "opponent"='@ minnesota north stars' AND "december">30;