We can put this information into two equations:
7 booklets = 140 stamps
3 booklets = 60 stamps
Let us then focus on one equation to find the relationship:
7 booklets = 140 stamps
If we put that into a fraction, we get 

 or 

.
This means that for every booklet, Ashley gets 20 stamps; or rather, each booklet has 20 stamps.
We can then see that this relationship holds true for the second equation as well:

 or 

.
To write a general equation for this relationship using 
p for the number of postage stamps, and 
b for the number of booklets:
p = 20b
Where 
b is equal to 
p.
 
        
        
        
The least number of books that could be in the box is 30. The number of books in the box could be any number that is a multiple of 30.
        
             
        
        
        
Answer:
(x + 9)(x - 8)
Step-by-step explanation:
f(x) = x^2 + x - 72
      = x^2 - 8x + 9x - 72
      = (x^2 - 8x) + (9x - 72)
      = x(x - 8) + 9(x - 8)
      = (x + 9)(x - 8)