All it takes for a relation to be a function is for each possible first number of a pair there's only one possible second number. 
So if any of the sets has two pairs with the same first number, that one's not a function.
The last one has (3,2) and (3,5) so isn't a function.
 
        
             
        
        
        
You said that 'A is 30' right there in the equation 
so it would be 
Xsquared=30
        
             
        
        
        
Answer:
   
Step-by-step explanation:
When you simplify the numerator and the denominator, you find they both have denominators of xy. So, the ratio of those is the ratio of their numerators.
   