1. The problem statement, all variables and given/known data http://img818.imageshack.us/img818/4065/thvs.jpg [Broken] 3. The attempt at a solution Calculating the Thevenin Resistance there I get 16Ω - the book however says it's 3Ω. The way I see 3Ω being calculated is if 4Ω were in parallel with 6Ω + 6Ω - however they all appear to be in series. I'm assuming the 1Ω resistor is replaced by an open-circuit?