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.
Esma can fit 3 packages in the box because 20+10+10=30 and 5+2+2=9 so if you add up 9 three times you get 27 and that is the closest number you can get before going over.