tolong jawab ..................

x + y + z = 5
x - y + z = 9
------------------ --
2y = -4
y = -2

x + y + z = 5 => x - 2 + z = 5 => x + z = 7
2x + 2y + 3z = 13 => 2x + 2(-2) + 3z = 13 => 2x + 3z = 17

x + z = 7 |3| 3x + 3z = 21
..................... 2x + 3z = 17
---------------------------------- --
...................... x = 4

x + z = 7 => 4 + z = 7 => z = 3

(x, y, z) = (4, -2, 3)