Write the augmented matrix for each system of equations.

The augmented matrix for a system of equations represent both  the coefficients  and the constant on the other side of the equal sign.

Each column contains the coefficients for a single variable.

In this case

[  5      -4      -6     {   -3    ]
[   1     -3       1     {    -1   ]
[  -3    -6        7     {    1    ]

Answer is d. staying organized