1. A craftsman named William Barnes builds two kinds of birdhouses, one for wrens and a second for bluebirds. Each wren birdhouse takes 4 hours of labor and 4 units of lumber. Each bluebird house requires 2 hours of labor and 12 units of lumber. The craftsman has available 48 hours of labor and 120 units of lumber. Wren houses yield a profit of $8 each and bluebird houses yield a profit of $15 each. (a) The aim of the objective function for William should be to (b) Define all decision variables (c) State the objective function (d) State the constraints the objective value. (e) Use Excel solver to obtain the optimal solution and optimal value of this problem