1. The problem statement, all variables and given/known data 2. Relevant equations V= iR Kirchoff's law for voltage 3. The attempt at a solution On the left-most part of the circuit , I did use KVL (voltage law) and I ended up with Vs = i0 (R1+R2) which basically boils down to i0(2R) since R1 = R2 =R3 ... I'm not even sure if both parts of the circuits are parallel or not... I'm kinda lost .