Add (1) and (2): (4). 5x+3z=-5; eliminate y from (2) and (3): subtract 2(2) from 3(3):
33x+9z-2x-4z=-57-42, (5) 31x+5z=-99.
Eliminate z from (4) and (5): 3(5)-5(4): 93x-25x=68x=-297+25=-272, so x=-4.
Substitute x=-4 in (4): -20+3z=-5, 3z=15, z=5.
Substitute for x and z in (1): -16+3y+5=-26, 3y=-26+11=-15, y=-5.
Check out answer in all original equations: -16-15+5=-26; -4+15+10=21; -44+10+15=-19.
ANSWER: x=-4, y=-5, z=5.