An electronics manufacturer has an option to produce six styles of cell phones. Each of these devices requires time, in minutes, on three types of electronic testing equipment, as shown in the table at the bottom of this page. The first two test devices are each available for 120 hours per week. Test device 3 requires more preventive maintenance and may be used only for 100 hours each week. The market for all six cell phones is vast, so the manufacturer believes that it can sell as many cell phones as it can manufacture. The table also summarizes the revenues and material costs for each type of phone. In addition, variable labor costs are $15 per hour for test device 1, $12 per hour for test device 2, and $18 per hour for test device 3. Determine the product mix that would maximize profits. Formulate the problem as an LP model and solve it by using Excel.