Helena Company reports the following total costs at two levels of production.

10,000 Units

20,000 Units

Direct materials

$20,000

$40,000

Maintenance

8,000

10,000

Direct labor

17,000

34,000

Indirect materials

1,000

2,000

Depreciation

4,000

4,000

Utilities

3,000

5,000

Rent

6,000

6,000

Classify each cost as variable, fixed, or mixed.