Answer:
7 book cases
Explanation:
Add 115 to itself until you reach past 360 (there is a remainder). 115 added 3 times is 345. 115 books=2 bookcases. So you multiply: 2×3=6. Since there is not enough room for all 360 books in 6 bookcases, you need 1 more, which makes it 7 bookcases.