Answer:
Since there are two cars, each car, then, drove 104/2 = 52 miles. But one car is traveling 8 miles per hour faster. 
Step-by-step explanation:
 
        
             
        
        
        
The first one is 6
The second one is 4
        
                    
             
        
        
        
Answer:
4 stones is the answer use basic mathematics 
 
        
             
        
        
        
"Combinations" isn't really the right word, because a combination doesn't take order of elements into account, and the outcome of a race certainly does depend on order. "Permutations" would be the correct term.
If 4 students are competing, then the race has
4! = 4 • 3 • 2 • 1 = 24
possible outcomes.