Identify each of the following costs incurred by Universal Sports Exchange in terms of its cost behavior-variable, fixed, mixed, or step.
a. Monthly sales staff payroll of $650 plus 6% sales commission on jerseys
b. $100 monthly rental for credit card processing equipment
c. Cost of goods sold of $14.80 per jersey
d. The cost of price tags attached to each jersey
e. Inventory insurance that costs $2 per $1,000 of sales
f. Website hosting cost of $25 per month