Macy Corporation's relevant range of activity is 7,200 units to 15,000 units. When it produces and sells 11,100 units, its average costs per unit are as follows: Direct materials Direct labor Variable manufacturing overhead Fixed manufacturing overhead Fixed selling expense Fixed administrative expense Sales commissions Variable administrative expense Average Cost per Unit $5.35 $3.80 $1.80 $3.50 $1.10 $0.80 $1.05 $0.70 If the selling price is $30.50 per unit, the contribution margin per unit sold is closest to: $10.95 $21.35 $7.15 $17.80