Linear Programming graphically in 3d

Consider the feasible region is given by inequalities , , . Suppose you maximize the function . And let be your slack variables. QUESTIONS 1. Identify ALL the solutions of the linear problem from the graph. 2. For each of the 6 corner points of the region, identify the corresponding non-basic variables. 3. Write the objective function in terms of the non-basic variables at the point (0,0,4).