Question: Tim and Donna will celebrate their 20th wedding anniversary in 2025. They started dating 3 years before they got married and met 2 years before that. When did they meet?
Answer: They'll celebrate their 20th wedding anniversary in 2025 which means they got married in 2025 - 20 = 2005. They started dating 3 years before they got married in 2005 which means they started dating in 2005 - 3 = 2002. And they met 2 years before they started dating which means they met in 2002 - 2 = 2000. The answer is 2000.

Question: Jack went to a supermarket with $100 and bought 4 bottles of water. Then his mother called him and asked him to buy twice as many bottles as he already bought. Each bottle cost $2. Finally, he also bought half a pound of cheese and 1 pound of cheese costs $10. How much money does Jack have remaining?
Answer: Jack's mother asked him to buy 2 * 4 = 8 bottles of water. Thus Jack bought 4 + 8 = 12 bottles of water in total. Altogether, the bottles of water cost 12 * $2 = $24. The cheese cost 1 / 2 * $10 = $5. So Jack spent $24 + $5 = $29 on water and cheese. Since he started with $100, he now has $100 - $29 = $71 left. The answer is 71.

Question: Calvin has been saving his hair clippings after each haircut to make a wig for his dog. He has gotten 8 haircuts and knows that he needs 2 more to reach his goal. What percentage towards his goal is he?
Answer: His goal is 10 haircuts because 8 + 2 = 10. He is 80% there because (8 / 10) x 100 = 80. The answer is 80.

Question: Hawkeye is driving to his aunt. He has to charge his battery for $3.5 per charge. If he charged his battery four times, and his battery charging budget was $20, how much money was he left with when he reached his aunt's place?
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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If each battery charge costs $3.5, the total expense of 4 battery charges is 4 * 3.5 = $14. After his expense on battery charging, his balance was 20 - 14 = $6. The answer is 6.