Answer
$= \displaystyle \frac{9}{28},\qquad x\neq-5$
Work Step by Step
Factor what we can:
$\displaystyle \frac{x+5}{7}\div\frac{4x+20}{9}=\frac{x+5}{7}\div\frac{4(x+5)}{9}$
Division with $\displaystyle \frac{a}{b}$ equals multiplication with $\displaystyle \frac{b}{a}.$
(neither a or b can be 0)
$=\displaystyle \frac{(x+5)}{7}\cdot\frac{9}{4(x+5)}$
...exclude the values that yield 0 in the denominator:
$x\neq-5$
... cancel common factors
$= \displaystyle \frac{9}{28},\qquad x\neq-5$
