Calculate the missing information based on the financial information below: Exercise 4: Net sales are $334,500; cost of goods sold is $132,300, and oper- ating expenses are $108,000. Find gross margin and net profit. Exercise 5: Net sales are $1,640,000, gross margin is $760,000, and oper- ating expenses are $354,780. Find cost of goods sold and net profit. Exercise 6: Cost of goods sold is $257,000, gross margin is $418,530, cost of net profit is $84,370. Find the net sales and the operating expense.