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. Salaries of human resources personnel
b. User’s guides
c. Shipping expenses
d. Advertising
e. Property taxes on general offices
f. Wages of telephone order assistants
g. President’s salary
h. Straight-line depreciation of computer equipment
i. Sales commissions
j. CDs
k. Packaging costs
l. Salaries of software developers