1. The problem statement, all variables and given/known data I have been given the above information and asked to find the current in the edge ac. s is the sink, t is the source. 2. Relevant equations Kirchoff's First Law, current in = current out. Kirchoff's Second Law, the sum of resistance.current for all vertices in a cycle = 0. 3. The attempt at a solution Firstly I have assumed that all currents connected to the sink go into the sink, and all connected to the source go away from the source. I have also assumed the current flows from c to b, and c to a. I have made these assumptions to make sure there cannot be an infinite cycle in the graph and I simply cannot see a way to solve this if the graph is not directed. So from kirchoff 1 i have: Icb - 10 - Ibs = 0 Itc - Ica - Icb = 0 Ita + Ica + 10 - Ias = 0 And from kirchoff 2: cycle tca : 6Itc + Ica - 3Ita = 0 cycle cab : Ica - 20 - 3Icb = 0 cycle bas : 20 + Ias - 2Ibs = 0 However I cannot seem to solve these simultaneously to get any closer to my result,and I'm not sure my initial assumptions about the direction of flow of current are valid, any hints/tips would be appreciated!