4) min 4x1 + 3x2 + 6x3 s. t. x1 + 0.5x2 + x3 ≥ 15 2x2 + x3 ≥ 30 x1 + x2 + 2x3 ≥ 15 x1,x2,x3 ≥ 0 a) find the optimal solution by entering this problem into excel. b) run the sensitivity report and use it to find the optimal solution to the dual problem [do not solve the dual by using solver]. c) formulate the dual problem. d) verify that the strong duality theorem and all complementary slackness conditions (there are six of them) hold.