I am trying solve the question shown in the picture below
(I am assuming the switch is down in the picture, I can't tell)
The equation that I am using is Vout/Vin = - Rf/Rin because there is negative feedback.
For 2a), I ignored R4 because there is no current input to the Op-Amp so I am assuming R4 can be neglected. I combined R2 and R3 so that the total resistance for Rf is 1000 ohms. I then substituted Vin as 20mv, Rin as 1ohm and rearranged to get Vout = -20V. I am unsure if I applied the right logic to this question and I am don't know how to solve 2b).
This circuit is different to other inverting Op-Amp circuits I have seen which is why I am struggling to answer it. Does anyone know how to approach a question like this? Thanks very much for your time