Natalie's sister had 8 small diaries in her locker. Last summer she bought double the number of diaries she had and then lost 1/4 of what she had. How many diaries does Natalie's sister have now? Let's answer step by step:
Natalie's sister bought 2 * 8 = 16 diaries. So she then had 16 + 8 = 24 diaries. Afterwards, she loses 1 / 4 * 24 = 6 diaries. So, Natalie's sister now has 24 - 6 = 18 diaries. The answer: 18.