Problem 3. (30 points) Develop the Branch-and-Bound (B&B) tree for each of the following problems, following the procedure discussed in class. For convenience, always select x1 as the branching variable in the first step (i.e., node zero). (a). (b). max z = 3x1 + 2x2 s.t. 2x1 +5x2≤9 4x1 + 2x2 ≥ 9 x10, x20 x1, x2 are integers (c). min z = 5x1 + 4x2 3x12x2 5 s.t. max s.t. 2x1 + 3x2 ≥7 x10, 20 x1, x2 are integers z = 5x1 +7x2 2x1 + x2 13 5x19x241 x10, x2 ≥ 0 x1, x2 are integers