Pine Street Inc. makes unfinished bookcases that it sells for $57.00. Production costs are $37.20 variable and $9.50 fixed. Because it has unused capacity, Pine Street is considering finishing the bookcases and selling them for $70.00. Variable finishing costs are expected to be $5.50 per unit with no increase in fixed costs. Prepare an analysis on a per unit basis showing whether Pine Street should sell unfinished or finished bookcases.