Lizzy: Santana has 7 brothers. 3 of them have birthdays in March, 1 of them has a birthday in October, 1 has a birthday in November, and another 2 of them were born in December. If Santana always buys each of her brothers a birthday present and a Christmas present, how many more presents does she have to buy in the second half of the year than the first half of the year?.
Me: Hmmm, let me think. I think this is the detailed solution:
Santana has 1 + 1 + 2 = 4 brothers with birthdays in the second half of the year. She has 7 brothers - 4 brothers = 3 brothers with birthdays in the first half of the year. Altogether, she has to buy 4 + 7 = 11 presents in the second half of the year. Therefore, she has to buy 11 - 3 = 8 more presents in the second half of the year. Final answer: 8.