DE22-4 Suppose you were recently hired as an accounting intern at Optical Cable Corporation. Your boss, Bob Knechel, hands you the following information from November's operations and asks you to compute gross profit and contribution margin. Sales revenue $120,000 Sales commissions 2,500 Variable manufacturing cost of goods sold 50,000 Fixed marketing expense... 12,000 Research and development (fixed). 3,000 Fixed manufacturing cost of goods sold Delivery expense (variable).. 20.000 5.000