1) not function because 6 number repeat in domain
2) Function
For 3 and 4 I guess it's
3) Function
4)not function 
If any number repeat twice in the domain that will be not a function
        
             
        
        
        
If i’m not mistaken, it should be 2/10, or 20/100. and it’s percentage would be 20%
        
                    
             
        
        
        
Answer:
#1. X=3 and #2. Y=9
Step-by-step explanation:
Glad i could help, give me a follow, so if you need help with any other question, im here.