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

### Instruction:
When 4 clubs are involved, what is the average number of fixtures?

### Inputs:
table_name: table, columns: ['Round', 'Date(s)', 'Clubs from the previous round', 'Clubs involved', 'Fixtures']

### Response:
SELECT AVG Fixtures FROM table WHERE Clubs involved = 4