6. (30 points) Duke Energy needs to determine how much electricity to produce from each of their generators in order to meet their demand in the next hour. They have 5 available generators. The generators differ in the fixed cost of operating the generator (which is paid only if the generator is turned on and produces a positive amount of electricity), the variable cost per MW, and the maximum amount of electricity (in MW) they can produce. The table below lists these values for each of the generators. Generator Fixed cost: F;($) Variable cost: G ($ per MW) Max Capacity: M, (MW) 1 2 3 4 5 700 500 450 300 250 4 5 8 7 9 300 250 200 500 400 Suppose that Duke Energy must produce electricity to meet demand of 600 MW this hour. (e) Suppose we have an additional constraint: If generators 1,2,3 are all turned on, then either generator 4 or generator 5 (or both) should be turned on. How to model this constraint