I think it is 568 if I’m not mistaken
        
             
        
        
        
So hmm notice the picture below
you have the center, and a point on the circle... all you need is the radius

then use that radius in the circle's equation
 
 
        
        
        
The answer will be (x-9) with a little two in the corner *2
        
                    
             
        
        
        
There are an infinite number of different equations that have 
x=2/3  as the solution, or as one of several solutions.
You didn't show us your list of choices, so we can't help you 
pick the right one.
Just take each choice, one at a time.  Write ' 2/3 ' in place of 'x' 
in each equation, and simplify everything.  You'll wind up with 
one equation that's true, and the others will say something that's 
nonsense.  
The one that's true is the one that has  x=2/3  as its solution.