Black book:
Check the third drawer by the chair and get the flashlight, then look under the bookshelf with the flashlight. Take the pencil. Open the black book and use the pencil on it.
Safe combination:
The red book is “7”, green book is “4”, and blue book is “5”. The paper behind the books reads “Safety box dial. Blue book is your left number 3, center number is in the green book 2, and red book is the right number -1”. This makes the combination 8, 9, 6.