Brilliant Books makes and sells two types of book covers, hard and paperback. Below is their product data: Hard cover Paperback cover Unit selling price $10.00 $6.00 Variable costs per unit $6.00 $3.00 Seventy percent of the sales units are in paperback. Annual fixed costs are $65 000 Determine the weighted average unit contribution margin. a. $3.60 b. $3.90 c. $7.00 d. $3.30