#### Answer

x = 1
y = 0
z = 4
w = -2

#### Work Step by Step

The reduced row-echelon form of the matrix is:
$\begin{bmatrix}
1 & 0 & 0 & 0 & |1\\
0 & 1 & 0 & 0 & |0\\
0 & 0 & 1 & 0 & |4\\
0 & 0 & 0 & 1 & |-2\\
\end{bmatrix}$
From reduced row-echelon form the solution is simple:
x = 1
y = 0
z = 4
w = -2