4x+y=5 y-2z=-7 adalah x+z=5 {(x,y,z)}.Nilai 4x+3y-6z adalah....

x + z = 5
z = 5 - x

y - 2z = - 7
y - 2(5 - x) = - 7
y - 10 + 2x = - 7
y + 2x = - 7 + 10
y + 2x = 3

4x + y = 5
2x + y = 3
-----------------(-)
2x = 2
x = 1

2x + y = 3
2(1) + y = 3
y = 3 - 2
y = 1

z = 5 - x
z = 5 - 1
z = 4

nilai 4x + 3y - 6z
= 4(1) + 3(1) - 6(4)
= 4 + 3 - 24
= (-17)