Example 17 Wood Built Bookshelves ( WBB) is a small wood shop that produces three types of bookshelves: models A, B, and C. Each bookshelf requires a certain amount of time for cutting each component, assembling them, and then staining them. WBB also sells unstained versions of each model. The times, in hours, for each phase of construction and the profit margins for each model, as well as the amount of time available in each department over the next 2 weeks, are given below. Model B Laborth) Profit Margin Cutting Assembling Staining Stained Unstained 1 4 7 $60 $30 05 3 $40 $20 2 6 8 $75 540 200 700 550 Labor available Since this is the holiday season, WBF can sell every unit that it makes. Also, due to the previous year's demand, at least 20 model B bookshelves (stained or unstained) 8 must be produced. Finally, to increase sales of the stained bookshelves, at most 50 unstained models are to be produced. Formulate and solve a linear program to determine what WBF should produce in order to maximize its holiday profits