1. The problem statement, all variables and given/known data a) Find Req of the circuit b) Find the potential difference across resistance R3 2. Relevant equations Resistors in parallel = (1/R1 + 1/R2 + 1/R3 + ...)^-1 Resistors in series = R1 + R2 + R3 + ... 3. The attempt at a solution a) R3 and R4 are in parallel --> [ (1/40Ω) + (1/50Ω) ]^-1 = 200/9 Ω R2 and R_34 are then in series --> 50Ω + (200/9)Ω = 650/9 Ω R1 and R_234 are then in parallel --> [ (1/40) + (650/9) ]^-1 = 25.7Ω b) This is the part I need help with as I'm clueless on even how to start. Any guide is appreciated.