I have problems Understanding systems Variable like this example

4x - 2y + z = 8

-y + z=4

2z = 4

4x - 2y + z = 8

Step 1: Add 2y to both sides 4x - 2y + z + 2y = 8 + 2y 4x + z = 2y + 8

Step 2: Add - z to both sides 4x + z + - z = 2y + 8 + - z 4x = 2y - z + 8

Step 3: Divide both sides by 4 4x 4 = 2y - z + 8 4 x

= 1/2 y + - 1 / 4 z + 2

-y + z = 4

Step 1: Add - z to both sides - y + z + - z = 4 + - z - y = - z + 4

Step 2: Divide both sides by - 1 - y - 1 = - z + 4 - 1 y

= z - 4

2z = 4

Step 1: Divide both sides by 2 2z / 2 = 4/2

=z=2