Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
December larger than 21, and a Opponent of Pittsburgh penguins had what average game?

### Inputs:
table_name: table, columns: ['Game', 'December', 'Opponent', 'Score', 'Record']

### Response:
SELECT AVG Game FROM table WHERE December > 21 AND Opponent = pittsburgh penguins