Solution :
a. Ink used for screen printing --- Variable
b. Warehouse rent of $8,000 per month plus $0.50 per square foot of storage used --- Mixed
c. Thread --- Variable
d. Electricity costs of $0.038 per kilowatt-hour --- Variable
e. Janitorial costs of $4,000 per month ---- Fixed
f. Advertising costs of $12,000 per month ---- FIXED
g. Accounting salaries --- FIXED
h. Color dyes for producing different colors of T-shirts ----- Variable
i. Salary of the production supervisor ---- FIXED
j. Straight-line depreciation on sewing machines ----- Fixed
k. Salaries of internal pattern designers ----- FIXED
l. Hourly wages of sewing machine operators ------ Variable
m. Property taxes on factory, building, and equipment ----- Fixed
n. Cotton and polyester cloth ---- VARIABLE
o. Maintenance costs with sewing machine company (the cost is $2,000 per year plus $0.001 for each machine hour of use.) ---- Mixed