[Question]The total number of whales in the sea this year is double what it was last year. If the World Animals Organization predicts that there will be 800 more whales in the sea next year, and the number of whales in the sea last year was 4000, calculate the total number of whales in the sea next year if the predictions are accurate.
[Answer]If there were 4000 whales in the sea three years ago, and their number doubled this year, then there are 2 * 4000 = 8000 whales in the sea this year. If the predictions come true, there will be 8000 + 800 = 8800 whales in the water next year. The answer is 8800.

[Question]Mike is 16 years old. His sister Barbara is half as old as he is. How old is Barbara going to be when Mike is 24 years old?
[Answer]Barbara is currently 16 years / 2 = 8 years old. Mike is going to be 24 years old after 24 years - 16 years = 8 years. So Barbara is going to be 8 years + 8 years = 16 years old. The answer is 16.

[Question]Tammy wants to run 3500 meters per week. She knows her track at school is 50 meters around. If she wants to run the same amount each day, how many loops should she make per day?
[Answer]She needs to run 70 laps in total each week, because 3500 divided by 50 equals 70. Since there are seven days in a week, she needs to run 10 laps per day because 70 divided by 7 equals 10. The answer is 10.

[Question]John's pool is 5 feet deeper than 2 times Sarah’s pool. If John’s pool is 15 feet deep, how deep is Sarah’s pool?
[Answer]
Let x be the number of feet in John’s pool. 2 * x + 5 = 15. 2x = 10. x = 5. The answer is 5.