Houseco Developers is considering erecting three office buildings. The time required to complete each and the number of workers required to be on the job at all times are shown below. Once a building is completed, it brings in the following amount of rent per year: building 1, $60,000; building 2, $40,000; building 3, $50,000. Houseco faces the following constraints: During each year, 60 workers are available. At most, one building can be started during any year. Building 2 must be completed by the end of year 4. a) (5 points) Formulate an IP that will maximize the total rent earned by Houseco through the end of year 4. b) (15 points) Solve the formulated IP by the branch and bound method. You can solve the LP relaxations by any methods/softwares. Duration of Project (Years) Number of Workers Required Building 1 2 2 2 30 20 20 3 3