We have 5 projects for execution over the next 3 years. The expected return for each project and funds needed and available each year (in thousands dollars) are given as follows: Project 1 Project 2 Project 3 Project 4 Project 5 Funds available Year 1 5 4 3 7 8 25 Year 2 1 7 9 4 6 24 Year 3 8 10 2 1 10 23 Return 20 40 20 15 30 Which of the five projects should be executed over the three years knowing that a) Exactly two of the projects 3, 4 and 5 must be done. b) If project 1 and 3 are done project 5 must be done. c) Project 1 and 2 must be undertaken simultaneously. Formulate a linear programming which maximize the return. (setup and do not solve)