jmc

Since both lines intersect at the point $(-4,-7)$, line $n$ must pass through this point. We can substitute these coordinates into the equation $y=kx-7$ and solve for $k$ as shown: $$\begin{array}{rl}-7& =k(-4)-7\\ \Rightarrow -7& =-4k-7\\ \Rightarrow 0& =-4k\\ \Rightarrow \boxed{0}& =k\end{array}$$