Diketahui  x-2y= 5, 2x+3z=12; y+2z=3. Nilai x+y+z=

x-2y=5........(i)
2x+3z=12....(ii)
y+2z=3........(iii)
x+y+z=...?
x-2(3-2z)=5
x-6+4z=5
x+4z=11.....(iv)

(i) dan (iv)

2x+3z=12
2(11-4z)+3z=12
22-8z+3z=12
-5z=-10
z=2

2x+6=12
x=3

y+4=3
y=-1

x+y+z=3-1+2=4