Tanek Industries manufactures and sells three different models of wet-dry shop vacuum cleaners. Although the shop vacs vary in terms of quality and features, all are good sellers. Tanek is currently operating at full capacity with limited machine time. Sales and production information relevant to each model follows. Product Economy Standard Deluxe Selling price $44 $73 $145 Variable costs and expenses $17 $26 $61 Machine hours required 0.5 0.8 1.5 Calculate contribution margin per unit. Product Economy Standard Deluxe Contribution margin per unit Economy $ Standard $ Deluxe $