Hey there!
This is a multiplication word problem. If we think fo all 6 shelves each having 30 books on them, we could do:
30 + 30 + 30 + 30 + 30 +30 to get how many total books we have.
But that's where the beauty of multiplication comes in.
We can just multiply 30 times 6 to get 180 books about animals.
Hope this helps!