R = {10; 15; 20}
S = {20; 25}
R U S = {10;15; 20; 25;
        
             
        
        
        
Answer:
D. -10
Step-by-step explanation:
The sum of a triangle = 180°, therefore,
64° + 63° + x + 63 = 180°
Add like terms 
x + 190° = 180°
Subtract 190 from each side 
x + 190 - 190 = 180 - 190
x = -10
 
        
             
        
        
        
Answer:
step 2
Step-by-step explanation:
 
        
             
        
        
        
Answer:
y=4
Step-by-step explanation:
if y+2=6, you can subtract 2 from both sides, giving you y=6-2. 6-2=4, which is y.
 
        
                    
             
        
        
        
Step-by-step explanation:
"Is" means equals.  "Less than" means subtracted from.
28 = k - 12
Add 12 to both sides to solve for k:
k = 40