The following is a partial income statement for Duncan Corporation for 2019: Duncan Corporation Projected Income Statement For the Year Ended December 31, 2019 $15,000 $2,250 2,100 2,650 750 7,750 $ 7,250 Sales revenue (750 units at $20) Manufacturing cost of goods sold: Direct materials used Direct labor Variable manufacturing overhead Fixed manufacturing overhead Gross margin Selling expenses: Variable costs Fixed costs Administrative expenses: Variable costs Fixed costs Total selling and administrative expenses Operating income $1,100 950 900 620 3,570 $ 3,680 a. How many units of its product will Duncan Corporation have to sell to break even? b. What will be Duncan Corporation's operating income if sales volume increases by 40 percent