X + y = 6
x - 6y = -9
Subtract the equations, you get:
y - (-6y) = 6 - (-9)
7y = 15
y = 15/7
x + 15/7 = 6
x + 15/7 = 42/7
x = (42-15)/7
x = 27/15
None of your answer choices are correct, since the solution to the systems of equation is (27/15, 15/7)
        
             
        
        
        
The student went wrong in step three.  the solutions should have been -3 and 5
        
             
        
        
        
Sum of interior angles in a pentagon=540°
148+112+2x+2x+10+90=540
360+4x=540
4x=540-360
4x=180
x=180/4
x=45°
 
        
             
        
        
        
Answer: C all real numbers
Step-by-step explanation:
I got the answer right on Edge
 
        
             
        
        
        
The mean is 
7+10+13+4+12+21+10+3/8
=80/8
= 10
Hope it helps
Mark as brainliest.