Answer:
(1) x-y-2z=-6 , (2) 3x+2y=-25 , (3) -4x+y-z=12
Explanation:
Multiply (3) by 2,
-8x + 2y - 2z = 24
subtract above equation from (1)
9x - 3y = -30 --> 3x - y = - 10
subtract above equation from (2)
3y = -15 --> y = -5
Put y value back into (2)
3x + 2(-5) = -25 --> 3x - 10 = -25 --> 3x = -15 --> x = -5
Put x and y values into (3)
-4(-5) + (-5) - z = 12 --> 20 - 5 - z = 12 --> 15 - z = 12 --> z = 3
Hope its right good luck!!