Two ideal dc sources and a resistor with lengths involved

[Yarnzorrr]

Ive been given an assignment with the question being question 13of the following pdf:
http://vlsi-eda.cm.nctu.edu.tw/course/ICT_12Summer/hw/HWCh4.pdf
(note this isn't my actual assignment i just found this one on the internet that happened to be the same question that i was looking for)

Im really lost, i have no idea how to even start to tackle this problem! It looks like some form of node analysis but the involvemt of lengths isn't somethingthat I've seen before. Just a few hints on how to do this would be greatly apreciated..

 

[uart]

You just have to replace the wires in the circuit with their corresponding resistance. That is, 2x $r x$ on the left hand side and 2x $r (L-x)$ on the right.