Furnco manufactures desks and chairs. Each desk uses 4 units of wood, and each chair uses 3 units of wood. A desk contributes $40 to profit and a chair contributes $25. Marketing restrictions require that the number of chairs produced be at least twice the number of desks produced. There are 20 units of wood available. Furnco wants to maximize its profit. Formulate a LP model for Furnco in a spreadsheet and solve it to find out how many desks and how many chairs it should produce.