P11-1 Calculating Costs and Break-Even [LO3] Night Shades Inc. (NSI) manufactures biotech sunglasses. The variable materials cost is $2 per unit, and the variable labor cost is $3.4 per unit. a. What is the variable cost per unit? b. Suppose the company incurs fixed costs of $490,000 during a year in which total production is 318,500 units. What are the total costs for the year?