Answer:
The augmented matrix is ...
![\left[\begin{array}ccc0&-2&7&10\\9&5&0&1\\2&0&1&-5\end{array}\right]](https://img.qammunity.org/2019/formulas/mathematics/high-school/kbo16quzk38zdejjq70l2xy7l6wipyh9db.png)
Explanation:
Missing variables essentially have a coefficient of zero. Coefficients are listed in the same order in each row, and the matrix is "augmented" by the column of constants on the right side of each equation.