Tamlin Architectural is building a new, green apartment building downtown. In order to maintain the building's eco-friendly status, the carbon footprint of the building's heating systems needs to be kept as low as possible. The architectural firm has two kinds of heating units available. A solar heater costs $13,000, provides 400 W of heat, and has a carbon footprint of 0.6. A heat pump costs $4,500, provides 800 W of heat, and has a carbon footprint of 4.2. The architects need at least 12,000 W of heat for the building, and cannot spend more than $261,000 on the heating system. How many of each type of heater should Tamlin Architectural use in order to meet the criteria? Formulate a linear programming model for this situation. Solve this model using graphical analysis. Display your graph and the solution parameters. What is the cost difference between this option and the choice provided by the extreme point that provides the next smallest value of the carbon footprint? Create your graph using Microsoft Word or Excel.