Exercise 4: The following information is given for Northwest Company for 19X1: sales $6,300, purchases $7,100, beginning inventory $600, ending inventory $2,000, sales discounts $120, purchase discounts $160, sales returns and allowances $300, purchase returns and allowances $190, operating expenses $1,400. Compute: a. Net sales b. Net purchases c. Cost of goods sold d. Gross margin e. Net income or loss