#### Answer

$$\begin{bmatrix} 8&-7&4&\vdots&12 \\ 3&-5&2&\vdots &20\end{bmatrix}$$

#### Work Step by Step

In order to write a matrix that would solve a linear equation, we write the coefficients of each variable in their own column. Thus, we find:
$$\begin{bmatrix} 8&-7&4&\vdots&12 \\ 3&-5&2&\vdots &20\end{bmatrix}$$