Answer
$x=-4$
Work Step by Step
The given function is
$\Rightarrow r(x)=-5x-1$
Substitute $19$ for $r(x)$.
$\Rightarrow 19=-5x-1$
Add $1$ to each side.
$\Rightarrow 19+1=-5x-1+1$
Simplify.
$\Rightarrow 20=-5x$
Divide each side by $-5$.
$\Rightarrow \frac{20}{-5}=\frac{-5x}{-5}$
Simplify.
$\Rightarrow -4=x$
