Step 1: Understanding the Concept
The Zener diode in breakdown holds the voltage across itself and the parallel resistor at \(V_z\).
Step 2: Check Breakdown
Without the Zener, the voltage across \(R_2\) would be \(18 \times \dfrac{1800}{800 + 1800} \approx 12.5\text{ V}\), which is more than 9 V. So the Zener conducts and holds 9 V.
Step 3: Currents
Total current \(I = \dfrac{18 - 9}{800} = 11.25\text{ mA}\)
Current in \(R_2\): \(\dfrac{9}{1800} = 5\text{ mA}\)