Answer:
b
Step-by-step explanation:
 
        
             
        
        
        
Answer:
I do not know if there is this worksheet online which comes with answers, but you can post questions here on brainly, and I can help you clarify them!!
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140 degrees because an angle of a circle is 360 degrees and you can subtract these angles from it to get 140 degrees
        
                    
             
        
        
        
  5x - 2y + 1z = 8 ⇒   5x - 2y + 1z = 8
-9x + 2y + 2z = 5 ⇒ -9x + 2y + 2z = 5
-9x -  2y -  5z = 4             -4x + 3z = 13
 5x -  2y + 1z = 8
-9x + 2y + 2z = 5 ⇒ -9x + 2y + 2z = 5
-9z -  2y -  5z = 4 ⇒ -9x -  2y -  5z = 4
                                        -18x - 3z = 9
     -4x + 3z = 13
    -18x - 3z =   9
           -22x = 22
            -22    -22
                x = -1
    -18x - 3z = 9
-18(-1) - 3z = 9
       18 - 3z = 9
     - 18       - 18
             -3z = -9
              -3     -3
                z = 3
    5x - 2y + z = 8
5(-1) - 2y + 3 = 8
     -5 - 2y + 3 = 8
     -2y - 5 + 3 = 8
           -2y - 2 = 8
                + 2 + 2
                -2y = 10
                 -2     -2
                   y = -5
          (x, y, z) = (-1, -5, 3)