Ships Ahoy is a small company that makes model sailboat kits priced at $120.The costs of the materials that go into each kit are $45.It costs $5 in labor to assemble a kit.The company has monthly expenses of $1,000 for rent and insurance, $200 for heat and electricity, $500 for advertising, and $3,500 for the monthly salary of its owner.Ships Ahoy's unit variable cost is: