E20-25 Computing contribution margin in total, per unit, and as a ratio Complete the table below for contribution margin per unit, total contribution margin, and contribution margin ratio: Number of units Sales price per unit Variable costs per unit 1,720 units $1,800 720 $ 4,500 3,600 4,620 units $5,550 1,665 Calculate: Contribution margin per unit Total contribution margin Contribution margin ratio