Solve this system by substitution, 16 points and brainliest to first answer! -x -y -z = -8
-4x +4y +5z = 7
2x+2z=4
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- x - y - z = - 8 (1)

- 4x + 4y + 5z = 7 (2)

2x + 2z = 4 (3)

From (3): x + z = 2

                     x = 2 - z (4)

Substitute (4) into (1),

- x - y - z = - 8

- (2-z) - y - z = - 8

- 2 + z - y - z = -8

- 2 - y = - 8

2 + y = 8

Therefore, y = 6

Substitute y = 6 and (4) into (2),

- 4x + 4y + 5z = 7

- 4(2 - z) + 4(6) + 5z = 7

- 8 + 4z + 24 + 5z = 7

9z + 16 = 7

9z = - 9

Therefore, z = - 9

Substitute z = - 9 into (4),

x = 2 - z

x = 2 - (-9)

x = 2 + 9

Therefore x = 11

Solution:

x = 11

y = 6

z = -9

b.) divide by -5.

step-by-step explanation:

21.4 i did it already for s1

step-by-step explanation: