Tirri Corporation has provided the following information: Cost per Unit Cost per Period Direct materials $ 6.85 Direct labor $ 3.90 Variable manufacturing overhead $ 1.25 Fixed manufacturing overhead $ 22,500 Sales commissions $ 1.00 Variable administrative expense $ 0.55 Fixed selling and administrative expense $ 7,500 If the selling price is $26.20 per unit, the contribution margin per unit sold is closest to