solve this equation x+2y+2z=6, -2x+4y+6z=-3, x+3y+z=6

#3 - #1

y - z = 0 or y = z

2x#1: 2x + 4y + 4z = 12
#2 : -2x + 4y + 6z = -3
add them,
8y + 10z = 9
sub in z=z
8z + 10z = 15
z = 9/18 = 1/2
y = 1/2
in #3
x + 3/2 + 1/2 = 6
x = 6-4/2 = 4

x=4, y=1/2, z = 1/2