Determine the optimum solution for each of the following LPs by enumerating all the basic solutions

Maximize z=x?1+2x2-3x3-2x4

?Subject to: x1+2x?2 +x3 +2x4 ?= 4   

x?1+2x??2-3x3+x?4? = 4

x?1,x?2,x3,x?4 ≥ 0

a) Express the problem in equation form. b) Determine all the basic solutions of the problem, and classify them as feasible and infeasible. c) Use direct substitution int he objective function to determien the optimum basic feasible solution d) Verify graphically that the solution obtained in (c) is the optimum LP solution. e) Show how the infeasible basic solutions are represented on the graphical solution space.