2x+y=-2 (1)

x+y-z=-4 (2)
3x+5y+z=0 (3)
solve the system
need help quick!

2 answers

add the last two:
4x + 6y = -4
from the 1st: y = -2-2x

sub into above new equation:
4x + 6(-2-2x) = -4
4x - 12 - 12x = -4
-8x = 8
x = -1

then y = -2+2 = 0

in the 2nd:
x+y-z=-4
-1+0-z=-4
-z=-3
z=3

x=-1
y=0
z=3
12x+4y+2z=-7 (1)
3x-12y+6z=-4 (2)
9x-16y+4z=-3 (3)
solve the system
just need the steps how to do it