CREATE TABLE table_name_6 (game INT, december VARCHAR, points VARCHAR, opponent VARCHAR)

Which Game has Points of 53, and an Opponent of @ minnesota north stars, and a December larger than 30?
SELECT AVG(game) FROM table_name_6 WHERE points = 53 AND opponent = "@ minnesota north stars" AND december > 30
SELECT AVG("game") FROM "table_name_6" WHERE "@ minnesota north stars" = "opponent" AND "december" > 30 AND "points" = 53