1. The problem statement, all variables and given/known data http://i36.tinypic.com/hugkyb.jpg 2. Relevant equations According to my book, if R3 = R2 and R4 = R1, I can use the following formula: Vo = (R2/R1)(V2 - V1). 3. The attempt at a solution We want R2/R1 to equal 5. This means that R3 and R2 must be 5*3,3 = 16.5 k(ohms). However, I don't know what to do with the inner resistance of V2 and Vo. Any suggestions?