Pada sistem persamaan

2x – z = 6 → z = 2x – 6

3x – 2z = 7

3x – 2(2x – 6) = 7

3x – 4x + 12 = 7

-x = 7 – 12

x = 5 ✔

z = 2x – 6 = 4 ✔

x + z = 5 + 4 = 9 ✔