the answer
2x - y + z = -3 (1)
2x + 2y + 3z = 2 (2)
3x - 3y - z = -4 (3)
(1) - (2) 3y +2z =5
3 .(1) - 2.(2) 3y+5z = -1
let 's solve
3y +2z =5
3y+5z = -1
z= - 2, and 3y =5+4=9, y=3, so 2x - 3 -2 = -3 implies x= 1
finally x=1, y=3 and z= -2
proof
2x - y + z = -3?? 2.1 - 3 -2 = -3 (true)
