Dapper Hat Makers is in the business of designing and producing specialty hats. The material used for derbies costs $4.50 per unit, and Dapper pays each of its two full-time employees $360 per week. If Employee A makes 15 derbies in one week, what is the variable cost per derby, and what is this worker’s fixed cost per derby? If Employee B makes only 12 derbies in one week, what are this worker’s variable and fixed costs per derby?