Let
y-------> number of books read during the month 
x------> number of picture of a book
we know that

in this problem
for 
calculate y

therefore
the answer is
The number of books read during the month
is 
A is the minimum value
B is the first quartile
The point with the line through it (next to C) is the median.
The point to the outside of the box is the third quartile.
D is the maximum value.
Hope this helped.
We have that
x²<span>-20x
</span><span>Group
terms that contain the same variable
</span>(x²-20x)
Complete
the square
(x²-20x+10²)------> (x-10)²
the answer is
the number must be 100