Fill in the blanks with integers, and select the correct operator ($+$ or $-$), to give an equation whose graph is the line that passes through the point $(-1,8)$ and is parallel to the graph of $4x + 3y = -8 - x - 15y.$
We want the equation to be of the form $4x + 3y = \dots.$ Because we want the line to be parallel to the graph of $4x + 3y = -8 - x - 15y,$ the left-hand side of our equation must be $4x + 3y.$ The right-hand side is the same for both equations, so
\begin{align*}
\text{RHS} &= -8 - x - 15y \\
&= -x - 15y - 8.
\end{align*}Hence, the graph of $4x + 3y = -x - 15y - 8$ is the line that passes through $(-1,8)$ and is parallel to the graph of $4x + 3y = -8 - x - 15y.$
To find the equation of this line, we replace $x$ and $y$ with $-1$ and 8, respectively, to get $4(-1) + 3(8) = -(-1) - 15(8) - 8.$ This simplifies to $32 = -1 - 120 - 8 = -129.$ Therefore, the equation is $\boxed{4x + 3y = -129}.$