The augmented matrix of a system of linear equations has been carried to the following by row operations. Solve the system.
\[\left [\begin{array}{ccccc|c} 1 & -1 & 2 & 4 & 6 & 2\\ 0 & 1 & 2 & 1 & -1 & -1\\ 0 & 0 & 0 & 1 & 0 & 1\\ 0 & 0 & 0 & 0 & 0 & 0 \end{array}\right ]\]
Is this matrix in reduced row-echelon form? If not, carry it to the reduced row-echelon form.
\[(\answer {-4s-5t-4}, \answer {-2+t-2s}, s,\answer {1}, t)\]

Source

[Nicholson] W. Keith Nicholson, Linear Algebra with Applications, Lyryx 2021, Open Edition, Problem 1.2.3 (d).