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:

	Year 1	Year 2	Year 3	Return
Project 1	5	1	8	20
Project 2	4	7	10	40
Project 3	3	9	2	20
Project 4	7	4	1	15
Project 5	8	6	10	30
Funds available	25	24	23

Which of the five projects should be executed over the three years knowing that

1. Exactly two of the projects 3 , 4 and 5 must be done.
2. If project 1 and 3 are done project 5 must be done.
3. Project 1 and 2 must be undertaken simultaneously.

Formulate a linear programming which maximize the return. (setup and do not solve)