Calculating Op Amp gain with voltage divider
Both circuits have the same gain.
R4 is simply just a load, connected to opamp's output. You can ignore it. Remember that output impedance of opamp si very low.
R3 is simply a resistor put between 0V and 0V, there is no current flowing through it, so you can ignore it too. Remember that opamp tries to keep inverting and noninverting input at the same voltage.