Tolong dijawab ya nmr 3 dan nmr 4

no. 3
x + y + z = 6...(1)
x + 3y+z = 8...(2)
2x + y+z = 8....(3)

pers (1) dan (2)
x + y + z = 6
x+3y + z = 8
__________-
-2y = -2
y = 1

pers (1) dan (3)
x + y + z = 6
2x+y + z = 8
__________-
-x = -2
x =2

x + y + z = 6
2 + 1 + z = 6
3 + z = 6
z = 6 -3
z = 3


x - z = 2 - 3 = -1