Answer:
B
Step-by-step explanation:
The domain is all possible values of x.  Here, x is the number of $5 nontaxable items.  So x must be an integer, and it can't be negative.  It is possible for x to be 0.  So x is all whole numbers.
 
        
             
        
        
        
Yes, It is reasonable. I think this because you are dealing with 60 blocks, and out of every 5 blocks there are 3 red. 5 goes into 60 12 times. 3 multiplied by 12 is 36. 36 is more than 32. So, I think that it is reasonable. If this explanation didn't make sense, then feel free to ask for more. I hope this helped!
        
             
        
        
        
Answer:
There are 7 parts in all.
9 makes up three of those parts.
9/3=3
3x7=21 vehicles
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
C) I and III only
Step-by-step explanation:
Let full pool is denoted by O
Days Hose x takes to fill pool O = a
Pool filled in one day x = O/a
Days Hose y takes to fill pool O = b
Pool filled in one day y = O/b
Days Hose z takes to fill pool O = c
Pool filled in one day z = O/c
It is given that
                          a>b>c

Days if if x+y+z fill the pool together = d
1 day if x+y+z fill the pool together 
I) d < c
d are days when hose x, y, z are used together where as c are days when only z is used so number of days when three hoses are used together must be less than c when only z hose is used. So d < c
III) 
Using (1)

Similarly

So,
