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I.   x+3y-2z=-9
II. 6x-4y+3z=29
III. 2x+2y+z=13
solving by elimination 
I and III
 x+3y-2z=-9
4x+4y+2z=26
 5x + 7y = 17
II and III
6x-4y+3z=29
-6x-6y-3z=-39
    -10y = -10
       y = 1 and x = 2   | 5x = 17-7y,  x = 10/5
x+3y-2z=-9 
OR x+3y+9 = 2z  
   14 = 2z       z = 7