The following data relate to a company that produces and sells a travel guide that is updated monthly Fixed costs Copy editing $6,000 Art work $2,000 Typesetting $72,000 Variable costs: $3.20 per copy w $4.00 per copy Printing and binding Bookstore discounts.. Salespersons' commissions. Author's royalties $0.50 per copy $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