Answer:
 {x,y,z} = {-116,28,37} 
Step-by-step explanation:
// Solve equation [3] for the variable  z  
  
  [3]    5z = -2x - 2y + 9
  [3]    z = -2x/5 - 2y/5 + 9/5
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// Plug this in for variable  z  in equation [1]
   [1]    5x + 9y + 9•(-2x/5-2y/5+9/5) = 5
   [1]    7x/5 + 27y/5 = -56/5
   [1]    7x + 27y = -56
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// Plug this in for variable  z  in equation [2]
   [2]    4x + 9y + 6•(-2x/5-2y/5+9/5) = 10
   [2]    8x/5 + 33y/5 = -4/5
   [2]    8x + 33y = -4
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// Solve equation [2] for the variable  y  
  
  [2]    33y = -8x - 4
  [2]    y = -8x/33 - 4/33
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// Plug this in for variable  y  in equation [1]
   [1]    7x + 27•(-8x/33-4/33) = -56
   [1]    5x/11 = -580/11
   [1]    5x = -580
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// Solve equation [1] for the variable  x  
   [1]    5x = - 580  
   [1]    x = - 116 
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// By now we know this much :
    x = -116
    y = -8x/33-4/33
    z = -2x/5-2y/5+9/5
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// Use the  x  value to solve for  y  
    y = -(8/33)(-116)-4/33 = 28
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// Use the  x  and  y  values to solve for  z  
  z = -(2/5)(-116)-(2/5)(28)+9/5 = 37 
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│Hope this helped  _____________________│     
│~Derelis ____________________________ │
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