In each of the following equations supply the missing term(s):

a. Net sales \(=\) Gross sales - \(\qquad\) + Sales returns and allowances).

b. Cost of goods sold \(=\) Beginning inventory + Net cost of purchases -

c. Gross margin \(=\) \(\qquad\) - Cost of goods sold.

d. Income from operations \(=\) \(\qquad\) - Operating expenses.

e. Net income \(=\) Income from operations + \(\qquad\)