Resistor Layout with respect to the circuit:
Ri1 Rf
-\/\/\/\- -\/\/\/\-
1k 1k
OP AMP
Ri2 R4
-\/\/\/\- -\/\/\/\-
1k 1k
The utter most right resistor, where the voltage marker is connected to, is just a load so ignore it.
Rf = R4 = Ri1 = Ri2 = 1kOhm
AUcl = Rf/Ri
AUcl = 1/1 = -1
Vout = AUcl × (Vin1-Vin2)
Vout = -1 × (10-6)
= -1 × 4
= -4V
