1. The problem statement, all variables and given/known data I've been reviewing my electrical theory and I'm having trouble trying to calculate an expression for the voltage gain for these two specific circuits. (Images c and d of the question.png attachment). I already know the answers, however I am unable to derive the same solution. Answers are given with my solution attempt. 2. Relevant equations Kirchoff's loop law and current junction law. Voltage gain = Output voltage/Input Voltage R_s is source resistance, R_L is load resistance. r_o is amplifier output resistance and r_i is amplifier input resistance. 3. The attempt at a solution I've attached my solution for b if it's unclear what I am asking. I'm pretty sure I've misunderstood something while working it out but haven't been able to figure out the correct steps. Any help is appreciated. Edit: Attachments are now there.