Solve the following SLE with the Gauss algorithm. Mark the pivot in every step.

a$)$

$2x+2y+2z=,8$

$3x+y-z=,4$

$-2x+3y+z=,17$

b$)$

$x_1+x_3=1$

$2x_1+2x_2=4$

$2x_1+2x_3=2$