The number of library books increased by 20% after it bought new books in May. The number increased by another 20% after someone donated 300 more books in June. Find the number of books in the library before it bought new books in May.
When you look at the problem, 300 is 20% of the books. if 300 is 20%, then 1500 is 100%. 1500 is the value after the original 20% that was added, so if the value is 1250, 20% added to that equals 1500.
