A glassblower makes glass decanters and glass trays on a weekly basis. Each item requires 1 pound of glass, and the glassblower has 15 pounds of glass available each week. A glass decanter requires 4 hours of labor, a glass tray requires only 1 hour of labor, and the glassblower works 25 hours a week.

The profit from a decanter is $50, and the profit from a tray is $10. The glassblower wants to determine the total number of decanters (x1) and trays (x2) that he needs to produce to maximize his profit.

a. Formulate an integer programming model for this problem.

b. Solve this model by using the computer.