Defining equations bf solution and nonbasic variables

Question

Problem:

Consider the following problem.

Minimize   Z =   x₁ + 2 x₂,

subject to

                   -x₁ + x₂    £ 15

                  2 x₁  + x₂    £ 90

                            x₂     ³ 30

                          and

                   x₁ ³ 0, x₂ ³ 0.

(a) Solve this problem graphically

(b) Develop a table giving each of the CPF solutions and the corresponding defining equations, BF solution, and nonbasic variables.