Answer:
Step-by-step explanation:
using the distributive property, the answer is -6.
 
        
             
        
        
        
4y=-21+5
4y=-16
y=4
simplified
        
                    
             
        
        
        
False 
foci of an ellipse cannot be outside the ellipse
        
                    
             
        
        
        
I'm not sure what operation you're using but for example, subtraction and addition are inverse operations and division and  multiplication are inverse operations