1. The problem statement, all variables and given/known data Find Req. 2. Relevant equations Series: R1 + R2 + ... Parallel: 1/(1/R1 + 1/R2 + ...) 3. The attempt at a solution There's no solution for this one in the book but I'm thinking that I can break this up into two parallel sets. Parallel1 = (R1*R4)/(R1 + R4) and Parallel2 = (R3*R2)/(R3 + R2). Is that correct?