4.2 +c = 8.1
c = 8.1 -4.2 = 3.9 . . . . subtract 4.2 from both sides
a.) 3.9 liters . . . . . is the appropriate choice
        
             
        
        
        
We use x to represent the price of the cheapest hat. Since the more expensive hat is twice the price of the cheaper one, we use 2x to represent it. Therefore x + 2x, or 3x, equals $75.12. Divide 75.12 by 3 to find x, which is 25.04. The more expensive hat is 2x, so we must multiply 25.04 by 2 to find the price of the more expensive hat. Therefore, the cost is $50.08. 
        
                    
             
        
        
        
13 and i cant see number 8