Eliminate z from equation 2 and 3: subtract â‘¢ from â‘¡: 2x+y=-1 and call this â‘£.
Double ①: 4x+4y+2z=-10 and call it ⑤.
⑤-②: x=-10.
Substitute x=-10 in â‘£: -20+y=-1, y=19.
Substitute for x and y in â‘ : -20+38+z=-5, z=-23.
Solution: x=-10, y=19, z=-23.