Answer:
2.1
Step-by-step explanation:
 
        
             
        
        
        
40/8=5
$5= 1gal.
5x10=50 
So 10 gallons of gas costs $50
        
                    
             
        
        
        
Answer:
6
Step-by-step explanation:
Label them as variables
A, B, and C
Now try and list them
ABC
ACB
BAC
BCA
CAB
CBA
There should be 6
The more mathematical way is using factorials 
So you would do 3! which is 3*2*1
This also gives you 6
 
        
                    
             
        
        
        
Answer:
245
Step-by-step explanation:
-6 cows produce 35 gallons
6 x 7 =42
so 7 x 35 = 245