The circuit shown below on the left has the following parameters: IS = 3 mA R1 = 6.8 kΩ R2 = 3.3 kΩ R3 = 3.9 kΩ This circuit is to be replaced by an equivalent one shown on the right, such that the voltage and current 'received' by an arbitrary load resistor RL are identical when connected to either circuit. Determine the value of the voltage source VX and the resistor RX in the equivalent circuit.