Answer:
[tex]=9-x-8y[/tex]
Step-by-step explanation:
[tex]9-\left(x+8y\right)[/tex]
[tex]\mathrm{Apply\:the\:distributive\:law}:\quad \:-\left(a+b\right)=-a-b[/tex]
[tex]-\left(x+8y\right)=-x-8y[/tex]