A bookstore is giving away free books every day. The equation f(x)=162−9x gives the number of free books, f(x), that remain to be given away after x days. Which of the following is the best interpretation of f(18)=0 in this context?
The bookstore has 18 free books to give away.
A
The bookstore will give away 18 free books in 9 days.
B
It will take 18 days to give away all the free books.