C.21 
5^2-4=21 
Explanation
        
                    
             
        
        
        
Answer: y=7
Step-by-step explanation:
 
        
                    
             
        
        
        
V=8, did it on equations solver
        
                    
             
        
        
        
Answer:
A. Rotation of 90° counterclockwise about the origin.
Step-by-step explanation:
If you look, You can see that the diagram has been rotated, you just have to figure out witch way. 
A. is your answer.