Linear programming problem

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There are 6 pieces of wooden boards of a furniture craftsman and has 28 hours of free time. Sells two types of libraries by the board. Type I library requires 2 wooden boards and 7 hours; The library requires a type II 1 plate and 8 hours. The selling price of 120,000 $ Type I library. The price is 80,000 $ type II library. According to want to maximize sales revenue Furnishers must be purchased from both models make how many of each?
Install problem as a linear programming model.