21. Consider the following LP problem: Min: 2 = x + y (0) 5.1.: 3.5x + y '5 7 (I) 0.51 + y 33 l (2) 8x +10}: 5 40 (3) .r. y 2 0 (4) a. Write this problem in standard form using slack and surplus variables. b. Graph the feasible region for this problem. c. Find the optimal solution for this problem. d. Use the simultaneous equations method to double check your graphical solution