Question

4.68 Find the Norton equivalent with respect to the terminal aibo in the circuits in Fig. 1.48 15kr WWW- zi b

i want to know the reason for only one step, not the answer for whole question.

In the first step, the answer says because 8mA current source and 20KΩ resistor are in parallel with 30V source, so thry will not influence the behavior of the circuit. Hence these two part can be reduced.

I dont understand this step, Could you explain why they will have no influence to the circuit in norton equivalent?