Exercise 3. A real estate developer is planning to build an apartment building specifically for graduate students on a parcel of land adjacent to a major university (The U, of course). Four types of apartments can be included in the building: efficiencies, and one-, two-, or three-bedroom units. Their sizes in square feet are 500, 700, 900, and 1,200, respectively. The developer believes the building should include no more than 15 one-bedroom units, 20 two-bedroom units, and 10 three-bedroom units. Local zoning ordinances do not allow the developer to build more than 45 units in this particular building location, and restrict the building to a maximum of 38,000 square feet (thanks, Coral Gables). The developer has already agreed to lease 5 efficiencies, 10 one-bedroom, and 8 two-bedroom units to a local rental agency that is a silent partner in this endeavor. Market studies indicate that the monthly rents for each unit size are $1,400, $1,800, $2,100, and $2,750, respectively. Write and solve a linear optimization model to decide how many rental units of each type to include in the developer's building plans in order to maximize their potential rental income