Answer:
9
Step-by-step explanation:
You do parenthesis first so 1+2=3
Then you do division 6 divided by 2=3 
Then you will multiply 3 by 3 so 9
This is known as pemdas
P=parenthesis
E=exponents 
MD=multiplication and division you do it left to right so if division is in front of multiplication then you do division
As=Addition and subtraction is also left to right
 
        
                    
             
        
        
        
28 + 6 = 34 and 34 - 3 = 31!!!!!!!
 
        
             
        
        
        
Liz would end up baking more cookies than sara. So the answer would be d