Cathy Company sells books to the public. Cathy's income statement for the first quarter of the current year is presented below: Sales $600,000 Cost of Goods Sold 420.000 Gross Margin 180,000 Operating expenses: Selling $73,500 Administrative 73,500 147,000 Operating income. $33,000 On average, a book sells for $50. 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? On average, a book sells for $50. 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? $60,000 $9,600 $18,000 $6,400 O $3,300