ANSWER
[tex]-1[/tex]EXPLANATION
We want to simplify the rational expression given:
[tex]\frac{8x-9}{9-8x}[/tex]To do this, rewrite the denominator and simplify:
[tex]a-b=-(b-a)[/tex]This implies that:
[tex]\begin{gathered} \frac{8x-9}{-(8x-9)} \\ \Rightarrow\frac{1}{-1} \\ \Rightarrow-1 \end{gathered}[/tex]That is the answer.