Need help with these questions super confusing! And we use Principle of optimality for second question.

Bus 190 Final Exam Dr. Oliver Yu Page 4/4 3a. (5 points) Find a minimal spanning tree for the following network (ignoring the arrows in the arcs) 3b. (5 points) Show the total distance of the tree. 4. (35 points) Find the shortest route from Node 1 (origin) to Node 9 (destination) in the following network (ignoring the arrows on the arcs). For full credits, you must apply the Principle of Optimality to identify systematically the successive closest node to the origin until the destination is reached; otherwise, you get 0 or negative points. 10 12