The Solution:
From the given graph, we have that the two complex numbers have only real parts. This means that:
![\begin{gathered} Z_1=4 \\ \\ Z_1=-4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/1oen8efpdk6bl33v1oaznyn5ql1yt4c92c.png)
We are required to plot the graph of
![Z_1-Z_2](https://img.qammunity.org/2023/formulas/mathematics/college/k0osk1gz8y3vxsn15lhome7h01iykgj5kk.png)
So,
![Z_1-Z_2=4--4=4+4=8](https://img.qammunity.org/2023/formulas/mathematics/college/dgms33vjai9g4i7xc9jt36thwm63tgr7ii.png)
To plot the required graph, we shall locate point +8 on the real line as mark in red color in the attached graph below: