Question 1139578
solve by substitution
2x+3y+2z=18
-4x+y-z=5
2z=-10
solution
z=10/2=5
by substitute z=5
-4x+y=10    y=10+4x  by substitution 
2x+3y=8
2x+3(10+4x)=8
2x+30+12x=8
14x=8-30=-22
x=-22/14=-11/7
y=10+4x
y=10-44/7
y=70-44/7
y=26/7
answer
x=-11/7    y=26/7    z=5