Q: Elizabeth has 10 reusable water bottles. She loses 2 water bottles at school. Then someone steals 1 of her water bottles at dance practice. To avoid any future theft of her water bottles, Elizabeth places 3 stickers on each of her remaining bottles. How many stickers does Elizabeth use in total on her water bottles?
A: Elizabeth has 10 - 2 - 1 = 7 water bottles. Elizabeth uses 7 * 3 = 21 stickers. The answer is 21.

Q: Maynard's dog dug 8 holes in the lawn. Maynard filled in 75% of the hole with dirt. How many holes remain unfilled?
A: 75% of the 8 holes in Maynard's lawn, or (75 / 100) * 8 = 6 holes, were filled in with dirt. Of the original 8 holes, 8 - 6 = 2 holes remain unfilled. The answer is 2.

Q: Betty is 60 years old, and she is the oldest person in the family. Her daughter is 40 percent younger than she is, and her granddaughter is one-third her mother's age. How old is the granddaughter?
A:
Betty's daughter is 40 / 100 * 60 = 24 years younger than she is. That means her daughter is 60 - 24 = 36 years old. So the granddaughter is 1 / 3 * 36 = 12 years old. The answer is 12.