Margo has determined the contribution margin ratio of a product to be $40\%.$ its selling price is $$50,$ while its cost consists of two variable costs and one fixed cost. The sole fixed cost is a selling and administrative cost. The variable selling and administrative cost is @$2\mathrm{.}50/$unit$.$ What is the variable manufacturing cost per unit? What is the gross margin of one unit of this product if there are no fixed manufacturing costs? What is the gross margin percentage for this product?