[Question]: Lauren sent 65 pieces of mail on Monday, 10 more pieces of mail on Tuesday than on Monday, 5 fewer on Wednesday than on Tuesday, and 15 more pieces of mail on Thursday than on Wednesday. How many pieces of mail did Lauren send?
[Answer]: Lauren sent 65 + 10 = 75 pieces of mail on Tuesday. He sent 75 - 5 = 70 pieces of mail on Wednesday. And sent 70 + 15 = 85 pieces of mail on Thursday. Therefore, he sent 65 + 75 + 70 + 85 = 295 pieces of mail.
So the answer is 295.

[Question]: A 25 story building has 4 apartments on each floor. If each apartment houses two people, how many people does the building house?
[Answer]: If each building floor has 4 apartments, we have 25 floors * 4 apartments / floor = 100 apartments. If each apartment has 2 people, 100 apartments * 2 people / apartment = 200 people.
So the answer is 200.

[Question]: Tracy has been collecting novels from her friends to donate to the Children For The Future charity organization. In the first week she collects a certain number of books. In the next five weeks, she collects ten times as many books as she did in the first week. How many books did she collect in the first week if she has 99 books now?
[Answer]:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Let's say the number of books she had in the first week is x. After six weeks, Tracy has x + x * 10 = 99 books. Combining like terms, we get 11x = 99. Dividing both sides by 11, we find that the number of books Tracy had in the first week is x = 9.
So the answer is 9.