Question

X+z=4 y+z=5 x+2y+4=17

Answer 1

X=4-z
y=5-z
2y=10-2z
x+2y=13=4-z+10-2z
13=14-3z
-1=-3z
1/3=z
x=4-1/3=11/3
y=5-1/3=14/3