[Question]John buys 1000 balloons. Each balloon holds 10 liters of air. If he buys 500-liter tanks of gas, how many tanks does he need to buy to fill all the balloons?
[Answer]He needs 1000 * 10 = 10000 liters of gas. So he needs 10000 / 500 = 20 tanks. The answer is 20.
Q: The math teacher would be happy if the class average test score was at least 85. There are 10 students in the class, 5 of which scored a 92 on the test and 4 of which scored an 80. What would the last student have to score to at least make the teacher happy?
A: 5 students scored a combined total of 92 * 5 = 460. 4 additional students scored a combined total of 80 * 4 = 320. 9 students therefore scored a combined total of 460 + 320 = 780. We know the total combined score for 10 students must be at least 85 average * 10 students = 850. Therefore, the last student must score at least an 850 - 780 = 70. The answer is 70.
Question: Mel is three years younger than Katherine. When Katherine is two dozen years old, how old will Mel be in years?
Answer: When Katherine is 2 dozen years old, she will be 2 * 12 = 24 years old. If Mel is three years younger than Katherine, then when Katherine is 24 years old, Mel will be 24 - 3 = 21 years old. The answer is 21.
[Question]Jordan's dog, Max, was born on the same day that Luka turned 4 years old. Luka is exactly 2 years older than is Aubrey. On Aubrey's 8th birthday, how many years old was Jordan's dog, Max?
[Answer]If Luka is exactly 2 years older than is Aubrey, then on Aubrey's 8th birthday, Luka was 8 + 2 = 10 years old. If Jordan's dog, Max, was born on the same day that Luka turned 4 years old, then when Luka was 10 years old, Max was 10 - 4 = 6 years old. The answer is 6.
Q: Ella spends 40% of the money she makes from babysitting on video games. Last year she spent $100. This year she received a 10% raise. What is Ella’s new salary?
A: Last year Ella made a total of $100 / (40 / 100) = $250. This year with her raise, Ella’s salary will be $250 * (110 / 100) = $275. The answer is 275.
Question: John writes 3 stories every week. Each short story is 50 pages. He also writes a novel that is 1200 pages each year. Each sheet of paper can hold 2 pages. Over 12 weeks, how many reams of paper does he need to buy if a ream contains 500 sheets?
Answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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He writes 3 * 50 = 150 pages a week. That means he writes 150 * 52 = 7800 pages of short stories a year. So he writes 7800 + 1200 = 9000 pages a year. So he needs 9000 / 2 = 4500 sheets of paper. That means he needs 4500 / 500 = 9 reams of paper. The answer is 3.