Chapter 3 Linear Systems and Matrices - 3.8 Use Inverse Matrices to Solve Linear Systems - 3.8 Exercises - Skill Practice - Page 214: 17

$$X=\begin{pmatrix}18&19&10\\ -3&-4&-2\end{pmatrix}$$

Isolating X by taking the inverse of the matrix, we find: $$X=\begin{pmatrix}1&5\\ 0&-2\end{pmatrix}^{-1}\begin{pmatrix}3&-1&0\\ 6&8&4\end{pmatrix} \\ X=\begin{pmatrix}18&19&10\\ -3&-4&-2\end{pmatrix}$$