6. A tile manufacturer has supplied the following data: Boxes of tiles produced and sold.. Sales revenue Variable manufacturing expense.... Fixed manufacturing expense Variable selling and administrative expense Fixed selling and administrative expense..$128,000 Net operating income. 580,000 .. $1,653,000 $784,000 $145,000 $132,000 What is the company's unit contribution margin? O so.23 per unit O $4.90 per unit O $3.10 per unit $1.80 per unit