Answer:
Step-by-step explanation:
Remark
You have to convert one of the numbers. It doesn't matter which one, but you can't simply divide one into the other the way the numbers stand.
Conversion
20 kilograms = 20 * 1000 grams / kg
20 kilograms = 20000 grams
Formula
Number of books = mass of bookcase / mass of 1 book
Givens
number of books = ??
mass of bookcase = 20000 grams
mass of one book = 500 grams
Solution
number of books = 20000 / 500
number of books = 40
Answer: 40 books = mass of bookcase
