Introduction to Management Science 12th Edition by Bernard Taylor

Exercise 45

State University has decided to reconstruct the sidewalks throughout the east side of its campus to provide wheelchair access. However, upgrading sidewalks is a very expensive undertaking, so for the first phase of this project, university administrators want to make sure they connect all buildings with wheelchair access with the minimum number of refurbished sidewalks possible.
Following is a network of the existing sidewalks on the east side of campus, with the feet between each building shown on the branches:

Determine a minimal spanning tree network that will connect all the buildings on campus with wheelchair access sidewalks and indicate the number of feet of sidewalk.