2x+6y+8z=6 (1)
3x—12y+7z=—3 (2)
4x—3y+4z=11 (3)
(1)+(3)*2
10x+16z=28
5x+8z=14 (4)
(1)*2+(2)
7x+23z=9 (5)
(5)*5-(4)*7
115z-56z=45-98
59z=-53
z=-53/59
x=(9-23z)/7=250/59
y=(3x+7z+3)/12=139/177