The following is a list of various costs of producing sweatshirts. Classify each cost as either a variable, fixed, or mixed cost for units produced and sold.

(a)	Lubricants used to oil machinery.
(b)	Warehouse rent of $6,000 per month plus $.50 per square foot of storage used.
(c)	Thread.
(d)	Electricity costs of $.025 per kilowatt-hour.
(e)	Janitorial costs of $2,000 per month.
(f)	Advertising costs of $10,000 per month.
(g)	Sales salaries.
(h)	Color dyes for producing different colors of sweatshirts.
(i)	Salary of the production supervisor.
(j)	Straight-line depreciation on sewing machines.
(k)	Patterns for different designs. Patterns typically last many years before being replaced.
(l)	Hourly wages of sewing machine operators.
(m)	Property taxes on factory, building, and equipment.
(n)	Cotton and polyester cloth.
(o)	Maintenance costs with sewing machine company. The cost is $2,000 per year plus $.001 for each machine hour of use.