Classify the total costs of each of the following as variable, fixed, mixed, or step.

a. Straight-line depreciation on a building

b. Maintenance costs at a hospital

c. Rent on a photocopy machine charged as a fixed amount per month plus an additional charge

per copy

d. Cost of goods sold in a bookstore

e. Salaries paid to temporary instructors in a college as the number of course sessions varies

f. Lumber used by a house construction company

g. The costs of operating a research department

h. The cost of hiring a dance band for three hours

i. Laser printer paper for a department printer

j. Electric power in a restaurant