2. (60%) For the following linear programming model, MaxZ=3x12x2+x3x4 Subject to: x1x2+x3+x45x2+x3x46x1,x2,x3,x40 We can obtain its row 0 of optimal (final) tableau form by using simplex method. (1) Write down the its dual problem. (20\%) (2) For this problem's dual problem, write down the values of dual variables and dy surplus variables. (10%) (3) Use dual theory to obtain the optimal Z value. (10%) (4) Use the complementary slackness property to find the value of primal variab (20%)