16. Let A and B be defined by

$$A = \begin{bmatrix}

1 & 1 & 1 \\

2 & 2 & 2 \\

-1 & 1 & -3

\end{bmatrix}$$

$$B = \begin{bmatrix}

0 & 2 & 1 \\

0 & 4 & 2 \\

0 & -2 & -1

\end{bmatrix}$$

Show that the column space of B is a subspace of the column space of A.