Answer:
90 degrees 
Step-by-step explanation:
 If two angles are supplementary they are a linear pair which means they form a straight line, and if you know a straight line equals 180 degrees which is the total degrees of a triangle. 
 Now if you have two supplementary angles and they are congruent that means not only are they right angles but its half of 180 so you divide these pair of 2 by 180 giving you your total of 90 degrees. 
 Have a nice rest of your day !
 
        
             
        
        
        
This one is simple since we already have the two x variables.equal. All we have to do is subtract the equations from one another to get the answer.
So i will subtract the left side by the other left side and the right side by the other right side
-8x - 8y -(-8x + 2y) = 0 -(-20)
distribute negative sign
-8x - 8y + 8x - 2y = 0 + 20
do the math
- 10y = 20
Y = -2
plug t into an equation
-8x -8 (-2) = 0
-8x + 16 = 0
-8x = -16
x = 2
 answer (2, -2)
        
             
        
        
        
Answer:
You should stick with option D
 
        
             
        
        
        
Answer:
x=-4
Step-by-step explanation:
Dividing both sides by -3, you get x+2=-2. So x=-4.
 
        
                    
             
        
        
        
-2-(5•-3)= -2-(-15)
= -2+15
=13