# How do I multiply the matrix ((3, 0, -19),(0, 7, 1), (1, 1/5, 2/3)) by -6?

$\left(\begin{matrix}a & b \\ c & d\end{matrix}\right)$ multiplied by some constant $k$. You would then have:
$k \left(\begin{matrix}a & b \\ c & d\end{matrix}\right)$=$\left(\begin{matrix}k a & k b \\ k c & k d\end{matrix}\right)$
So in your case, with k=-6 and $\cdot$ denoting multiplication, and we have:
$- 6 \left(\begin{matrix}3 & 0 & - 19 \\ 0 & 7 & 1 \\ 1 & \frac{1}{5} & \frac{2}{3}\end{matrix}\right) = \left(\begin{matrix}- 6 \cdot 3 & - 6 \cdot 0 & - 6 \cdot - 19 \\ - 6 \cdot 0 & - 6 \cdot 7 & - 6 \cdot 1 \\ - 6 \cdot 1 & - 6 \cdot \frac{1}{5} & - 6 \cdot \frac{2}{3}\end{matrix}\right) = \left(\begin{matrix}- 18 & 0 & 114 \\ 0 & - 42 & - 6 \\ - 6 & - \frac{6}{5} & - 4\end{matrix}\right)$