co. has provided the following information: cost per unit cost per period direct materials $ 6.70 direct labor $ 3.80 variable manufacturing overhead $ 1.50 fixed manufacturing overhead $ 15,200 sales commissions $ 0.70 variable administrative expense $ 0.75 fixed selling and administrative expense $ 6,800 if the selling price is $20.80 per unit, the contribution margin per unit sold is closest to: