Use the BIP branch and bound algorithm to solve the following problem interactively.
Maximize
Z = 3 x1 + 5 x2
subject to
2 x1 + x2 <= 3
x1 + 3 x2 <= 6
xj >= 0 and is integer, for j = 1, 2.
Branch on x1 first if x1 is a fractional value in the solution of LP relaxation (if x1 is integer but x2 is fractional value, then branch on x2). When using the branch and bound algorithm, please show the complete solution tree AND clearly state the optimal solution x* and optimal Z value.