Q: Ken had fifty pencils, and he wanted to share some of them with his two friends, Manny and Nilo. Ken gave ten pencils to Manny and ten more pencils to Nilo than he gave to Manny. He kept the rest of the pencils. How many pencils did Ken keep?
A: Nilo received 10 + 10 = 20. Thus, Ken gave a total of 10 + 20 = 30. Therefore, Ken kept 50 - 30 = 20 pencils. The answer is 20.

Q: Jack has a stack of books that is 12 inches thick. He knows from experience that 80 pages is one inch thick. If he has 6 books, how many pages is each one on average?
A: There are 960 pages because 80 x 12 = 960. Each book is 160 pages because 960 / 6 = 160. The answer is 160.

Q: Mrs. Petersons bought 10 tumblers for $45 each. She paid with five $100 bills. How much change will Mrs. Petersons receive?
A:

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.
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The 10 tumblers amount to $45 x 10 = $450. Mrs. Petersons paid $100 x 5 = $500. So, her change will be $500 - $450 = $50. The answer is 50.