Martell Inc. makes unfinished bookcases that it sells for $60. Production costs are $30 variable and $10 fixed. Because it has unused capacity, Martell is considering finishing the bookcases and selling them for $72. Variable finishing costs are expected to be $8 per unit with no increase in fixed costs. Prepare an analysis on a per unit basis showing whether Martell should sell unfinished or finished bookcases.