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

### Instruction:
What is the league established before 1930 with the rayo vallecano club?

### Inputs:
table_name: table, columns: ['Club', 'League', 'Sport', 'Venue', 'Established', 'Capacity']

### Response:
SELECT League FROM table WHERE Established < 1930 AND Club = rayo vallecano