On the day of his 7th birthday, on March 13, 2007, a Tuesday, Carlos told his brother: "Counting from today, there are 2000 days until you turn 15." On what day of the week will his brother's birthday fall? How old will Carlos be on that day?
Dividing 2000 by 7, we get $2000=7 \times 285+5$. Therefore, 2000 days are equivalent to 285 weeks plus 5 days. Since March 13, 2007, was a Tuesday, counting the 5 remaining days, we have that the brother's birthday of Carlos will fall on a Sunday. Now, dividing 2000 by 365, we get $2000=365 \times 5+175$. Thus, 2000 days are approximately five and a half years, so Carlos will be 12 years old.