#### Answer

$\text{all real numbers except }$ $
b=-11$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
The domain of the given rational function, $
m(b)=\dfrac{b+9}{b+11}
,$ are the values of $
b
$ which will NOT make the denominator equal to $0.$
$\bf{\text{Solution Details:}}$
Solving for the values of $
b
$ that will make the denominator equal to $0$ results to
\begin{array}{l}\require{cancel}
b+11=0
\\\\
b=-11
.\end{array}
Hence, the domain is the set of $
\text{all real numbers except }$ $
b=-11
.$