Consider the 5 Ohm resistance resistor as a load of the original circuit to the left and define the parameters of the equivalent sources to the right.
Step 1. Changing the position of the switches define the output voltage Vo of the original circuit in the open-circuited mode (the resistance of the load is infinite) and the output current Is in the short-circuited mode (the resistance of the load is zero).
Step 2. Assign the voltage Vo to the voltage source and the current Is to the current source in the circuits to the right.
Step 3. Assign the resistance Vo/Is to the resistor in the circuits to the right.
Step 4. Connect the load to both real sources to the right and compare the voltage/current in the load of the original circuit with the voltage/current in the load of the sources to the right. If the sources are equivalent to the original circuit, the voltages/currents in the loads are the same.
Step 5. Make sure that the circuits remain equivalent when the resistance of the load is changed.
