CREATE TABLE table_name_30 (game INT, december VARCHAR, opponent VARCHAR)

December larger than 21, and a Opponent of Pittsburgh penguins had what average game?
SELECT AVG(game) FROM table_name_30 WHERE december > 21 AND opponent = "pittsburgh penguins"
SELECT AVG("game") FROM "table_name_30" WHERE "december" > 21 AND "opponent" = "pittsburgh penguins"