i think it might be B. :)
It's kinda like a parabola, but it isn't. it like
ax^2+bx+c
Answer: 13%
Step-by-step explanation:
The formula to find the simple interest is given by :-
, where P is the principal amount, r is rate of interest () in decimal and t is the time ( in years).
Given : P = $19,100 , I=$9932.00 and t= 4 years
Substitute all the above values in the formula , we get

In percent , 
Hence, the rate of interest = 13%
Its okay, the first half is completely irrelevant. All that matters is x and y. y = 16, because y is how much space the books take up. x = 8, since x is the number of books. All you have to find is the proportions. It is most likely talking about the proportions of the books, so you would need to find the length if each book. You know they will all be the same because it was previously mentioned each book is the same size. So the equation is:

Since 16/8 is 2, you would get 2in/book.
Hope that helps!
To round a number, you first have to determine what you are rounding to. in this case, it's the nearest dollar. Then, you determine whether to "round up," to the next higher number, or "round down," which is to stay at the number it's currently at, without the numbers following what you're rounding to. If the number after the place you're rounding to is equal to or higher than 5, you'll round up. If it's lower, you'll round down.
So, for your questions, the answers would look like this:
$8.98 rounds to $9.00, because 9 is bigger than 5.
$6.49 would round down to $6.00, because 4 is less than 5.
$2.51 rounds up to $3.00, because 5 is equal to 5.
$9.78 would round up to $10.00, because 7 is higher than 5.
$39.89 will round up to $40.00, because 8 is bigger than 5.