Pine Street Inc. makes unfinished bookcases that it sells for $58.31. Production costs are $37.53 variable and $10.13 fixed. Because it has unused capacity, Pine Street is considering finishing the bookcases and selling them for $73.89. Variable finishing costs are expected to be $6.72 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