$1-$ For the linear equations system

Duration: $75$min.

$x_1-x_2+2x_3-x_4=-1$

$2x_1+x_2-2x_3-2x_4=-2$

$-x_1+2x_2-4x_3+x_4=1$

$3x_1-3x_4=-3$

a$)$ Find the augmented matrix.

b$)$ Apply Gauss$-$Jordan Elimination to augmented matrix.

c$)$ Find solutions of the system.