Cathy Company sells books to the public. Cathy's income statement for the first quarter of the current year is presented below: Sales. Cost of Goods Sold Gross Margin. $600,000 420.000 180,000 Operating expenses: Selling $73,500 Administrative 73,500 147.000 Operating income $33,000 On average, a book sells for $60. Variable selling expenses are $5.50 per book, with the remaining selling expenses being fixed. The variable administrative expenses are 3% of sales revenue, with the remainder being fixed. If sales volume increases by 10% during the coming year, by how much should Cathy's operating income increase? O $18,000 $3,300 $9,600 $10,700 $60,000