Solve the linear system LaTeX: \displaystyle \begin{cases} 5 x - 6 y + 9 z = -28 \\ - 8 x - 6 y + 4 z = -50 \\ 4 x - 8 y - 5 z = 54 \\ \end{cases}

The Solution is LaTeX: \displaystyle (4, -1, -6) .