Should be the right answer ☺️
 
        
        
        
Answer:
x=19
Step-by-step explanation:
The perimeter of the right triangle is 
P=9+12+15 =36
The perimeter of the left triangle is 
P =x-7+ x-7+ x-7 = 3x-21
Set them equal
36 = 3x-21
Add 21 to each side
36+21 = 3x-21+21
57 = 3x
Divide each side by 3
57/3 = 3x/3
19 =x
 
        
                    
             
        
        
        
a)the y-intercept of function A is 9units below the y-intercept of function B
 
        
             
        
        
        
Answer:supplementary
Step-by-step explanation:By the angles shown