Answer: OPTION A
Step-by-step explanation:
You can convert 30 kilograms to grams ([tex]1\ kilogram= 1,000\ grams[/tex]), then:
[tex](30\ kilograms)(\frac{1,000\ grams}{1\ kilogram})=30,000\ grams[/tex]
Then, if a book in the bookcase has a mass of 400 grams and you need to find the number of books of the same mass that would take to equal the mass of the bookcase, you can divide the weight of the bookcase (in grams) by the weigth of one of these books.
Therefore:
[tex]books=\frac{30,000\ grams}{400\ grams}\\\\books=75[/tex]
