The following data relate to a company that produces and sells a travel guide that is updated monthly: Fixed costs: Copy editing $6,000 Artwork 2,000 Typesetting 72,000 Variable costs: Printing and binding $3.20 per copy Bookstore discounts 4.00 per copy Salespersons' commissions 0.50 per copy Author's royalties 2.00 per copy Each book sells for $20.00. The company sold 8,000 books in June and 10,000 books in July. The degree of operating leverage for July is closest to (round your final answer to two decimal places. 3.48. 4.22. 4.48. 8.70