Consider the following tableau corresponding to a basic solution of a maximization LB with original non-negative variable X1, X2, X3 and slack/surplus variables X4, X5, X6: Z X X2 X3 X4 X5 Xo RHS Z 1 0 -5.5 C3 0 0 7.5 48 X4 0 0 212 -1 1 0 1 10 X5 0 0 -1 1 0 1 -1 5 Xi 0 1 3 -1 0 0 1 6 (1) Assuming X2 is selected to enter the basis, if X4 is selected to exit the basis based on the minimum ratio test, the value of tableau entry 12 must be at least ? (2)By analyzing the current objective function value and the values of the original variables in the current basic solution, we determine that the original cost coefficient of x1(i.e., C) for this LP is equal to