Question 913649
x+y=2,
y+z=7,
z+w=13,
x+w+8


1,1,0,0,2
0,1,1,0,7
0,0,1,1,13
1,0,0,1,8
No solution


x+y=2,
y+z=7,
subtract
x-z=-5

x+w=8
z+w=13,
subtract
x-z=-5