Pine street inc. makes unfinished bookcases that it sells for $57.41. production costs are $37.50 variable and $9.99 fixed. because it has unused capacity, pine street is considering finishing the bookcases and selling them for $74.67. variable finishing costs are expected to be $8.31 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.