Question: A real estate developer will build two different types of apartments in a residential area: one-bedroom apartments and two-bedroom apartments. In addition, the developer will build either a swimming pool or a tennis court in the area that serves the residents. The swimming pool costs $2.1 million and the tennis court costs $1.8 million. If the swimming pool is built, the number of one-bedroom apartments must be at least triple the number of two-bedroom apartments. If the tennis court is built, the number of one-bedroom apartments is at most one-half of the number of two-bedroom apartments. Each one-bedroom apartment is expected to have a revenue of $50,000 whereas each two-bedroom apartment is expected to have a revenue of $55,000. The site can have at most 11,000 apartments. Please formulate a mathematical model to help the developer maximize the total profit. Please use GAMS to find the optimal solution and optimal value.