Just add to find X
20 + 60 = 80
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X = 80
To make sure plug it in
80 - 60 = 20
The equation is true
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x = 80 is your answer
        
             
        
        
        
C = 84 degrees
A = 2B
C = A + 20
A + B + C = 180
A = 2B 
A/2 = B
A + (A/2) + (A+20) = 180
multiply each side by 2
2A + A + 2A + 40 = 360
combine like terms
5A + 40 = 360
subtract 40 from both sides
5A = 320 
divide both sides by 5
A = 64
C = A + 20
C = 64 + 20
C = 84
        
             
        
        
        
Answer:
I <em>think</em> it's the 2nd one. 
I didn't learn this topic yet. 
 
        
             
        
        
        
Answer:
The vertex is (5, 12)
Step-by-step explanation:
The vertex, from vertex form, is (h,k).
Vertex form is a(x - h)² + k
= 2(x - 5)² + 12
So h = 5, k = 12
The vertex is (5, 12).
I hope this helped!