Answer: Plug y into the bottom equation 
Step-by-step explanation:
It’s simple! You are given the value of y and the easiest step would just be to plug y in.
Hope this helps!
 
        
                    
             
        
        
        
Sarah will need 1/4 cup of blueberries to make a cup of jam.
        
                    
             
        
        
        
The answer is 6 because 21+9=30 and 30-6=24 and 24 is the number of students in the class.