A shoe producer is preparing the production schedule for two types of shoes, hiking boots and tennis shoes. To plan the production, he must use the following production time information:

	Machine A	Machine B	Sewing
Hiking Boots	2 hours	1 hour	2 hours
Tennis shoes	1 hour	2 hours	1 hour

That is, the production of each pair of hiking boots requires 2 hours on machine A, 1 hour on machine B and 2 hours in the sewing process. The available employee hours per week are as follows: for machine A, 60 hours; for machine B, 60 hours; for sewing, 80 hours. The producer obtains a revenue of $20 for each pair of hiking boots and $15 for each pair of tennis shoes produced.

1. How many of each type of shoes should be produced per week in order to maximize revenue? Write down the optimization problem that the producer has to solve and present your answer algebraically and graphically.
2. What is the maximum revenue obtained?