Applying KCL at the inverting node
(Vx -V- ) / 20000 = 0.002 + (V- - Vy) / 40000
2Vx - 2V- = 80 + V- - Vy
2Vx - 3V- + Vy = 80 --------------- (1)
Using voltage divider rule the voltage at the non-inverting input
V+ = 2(20000) / (20000+20000)
V+ = 1V
Due to virtual short, the voltage at the inverting input is equal to the voltage at the non-inverting input.
V
- = V
+
V- = 1V
Substituting in (1)
2Vx - 3(1)+ Vy = 80
2Vx + Vy = 77
Vy = 2Vx - 77
Is in the form of
Vy = mVx + b
Whre
m = 2
b = -77