Answer:
6kΩ
Step-by-step explanation:
If we assume that the entire circuit's current is 3 mA, then we can compute the resistance within the circuit with the application of Ohm's law:
V = IR
V/I = R
R = V / I
R = 18V / 3 mA
R = 6kΩ
Hence, the resistance of the circuit is 6kΩ.
Cheers.