ANSWER
The solutions are
[tex]x_1= \frac{9}{4} [/tex]
[tex]x_2= \frac{3}{5} [/tex]
[tex]x_3= \frac{2}{3} [/tex]
and
[tex]x_4=-\frac{ - 9}{5}[/tex]
EXPLANATION
Since the matrix is in the reduced row echelon form, the corresponding matrix equation becomes,
[tex]\left[\begin{array}{cccc}1&0&0&0\\0&1&0&0\\0&0&1&0\\0&0&0&1\end{array}\right] \left[\begin{array}{cccc}x_1\\x_2\\x_3\\x_4\end{array}\right] =\left[\begin{array}{cccc}\frac{9}{4} \\\frac{3}{5} \\\frac{2}{3} \\-\frac{9}{4} \end{array}\right][/tex]
If we carry out the matrix multiplication, we obtain,
[tex]x_1= \frac{9}{4} [/tex]
[tex]x_2= \frac{3}{5} [/tex]
[tex]x_3= \frac{2}{3} [/tex]
and
[tex]x_4=-\frac{ - 9}{5}[/tex]
