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

### Instruction:
which # / county is correct for year less than 1981 and chalmers as location?

### Inputs:
table_name: table, columns: ['School', 'Location', 'Mascot', '# / County', 'IHSAA Class', 'Year Joined', 'Previous Conference']

### Response:
SELECT # / County FROM table WHERE Year Joined < 1981 AND Location = chalmers