Answer:
[tex]12x+9[/tex] and [tex]99[/tex]° are supplementary to each other.
Step-by-step explanation:
Supplementary means that two angles added together make 180°.
Looking at the graph, you can see that angles [tex]12x+9[/tex] and [tex]99[/tex]° both combined make 180°, so they are considered supplementary.
