Intuit Inc. develops and sells software products for the personal finance market, including popular titles such as Quicken® and TurboTax®. Classify each of the following costs and expenses for this company as either variable or fixed to the number of units produced and sold:
a. Straight-line depreciation of computer equipment
b. Sales commissions
c. Advertising
d. Packaging costs
e. CDs
f. Shipping expenses
g. Salaries of customer support personnel
h. Salaries of software developers
i. Wages of telephone order assistants
j. User’s guides
k. President’s salary
l. Property taxes on general offices