Answer:
There are 30 books in the shelf.
Step-by-step explanation:
To solve this problem we can use a rule of three in such a way that 12 paperback mysteries are related to 40% of the books in the shelf in the same proportion that "x" total books are related to 100% of the books in the shelf. So we have:
12 -> 40%
x -> 100%
40*x = 12*100
40*x = 1200
x = 1200/40
x = 30 books
There are 30 books in the shelf.
I believe the answer would be A
