Answer:
The answer is X=10
Step-by-step explanation:
 
        
                    
             
        
        
        
5 x 5 x 5 
Expanded just means writing it out as you would solve it. So solving a cube would be multiplying the number by itself 3 times
        
                    
             
        
        
        
So if you want it to be 9 less than your number (x) then you would subtract nine. 
 So it would be: 
 x - 9. 
 So if your "number" is 12 then you would substitute x for 12 and it would be 12-9. The answer is 3. So 3 is 9 less than a number (12). 
I believe
        
             
        
        
        
The answer is D.
You’re welcome!