You take 480 and divide it by 15, because it says per gallon. so then if the car goes 480 miles with 15 gallons, you have to figure out how to find per gallon. you divide 480/15 and your answer is 32
        
                    
             
        
        
        
Just multiple them together and u get 693
        
             
        
        
        
Y = -15 is the answer and blah 
        
                    
             
        
        
        
I think the answer is c purplestar1