a) 70% of the books are nonfiction.
b) 35,000 nonfiction books.
If 30% of the books are fiction, we can use subtraction to determine what percentage of the books are not fiction.
100% total books - 30% fiction = 70% not fiction
In mathematics, "of" means multiplication. Since 70% of the books in the library are nonfiction, we can multiply 70% by 50,000 to find how many books are nonfiction. Take note that a percentage is equal to that number divided by 100.
70% * 50,000 = 0.7 * 50,000 = 35,000 nonfiction books
