He earns $80 from werewolf removal because 8 x 10 = 80. He earned $25 from vampire removal because 105 - 80 = 25. He removed 5 vampires from town because 25 / 5 = 5. There were 10 vampires because 5 / .5 = 10. There were 40 werewolves because 4 x 10 = 40. The proportion of werewolves that he removed was .2 because 8 / 40 = .2. The percentage of werewolves removed was 20% because 100 x .2 = 20.
The answer: 20
Reverse engineering the question: Van Helsing gets paid by the town to remove all the vampires and werewolves. He gets $5 per vampire and $10 per werewolf. He removes half the vampires and removes 8 werewolves, and earned $105. There were 4 times as many werewolves as vampires. What percentage of the werewolves did he remove?


Reasoning and answer: With half as many crickets as roaches, he has 12 / 2 = 6 crickets. With twice as many caterpillars as scorpions, he has 3 * 2 = 6 caterpillars. In total, he has 12 + 3 + 6 + 6 = 27 insects in his bug collection.
The answer: 27
What was the question?
Question: Calvin is a bug collector. In his collection, he has 12 giant roaches, 3 scorpions, half as many crickets as roaches, and twice as many caterpillars as scorpions. How many insects does Calvin have in his collection?


In the blue basket, there are 12 bananas + 4 apples = 16 fruits. The red basket holds half of this so there are 16 fruits in the blue basket / 2 = 8 fruits in the red basket.
The answer: 8
Reverse engineering the question: There are 12 bananas and 4 apples in the blue basket. The red basket holds half as many fruits as the blue basket. How many fruits are in the red basket?


Reasoning and answer: Skyler wrote 25 + 10 = 35 songs that made it on the top 100. He wrote 25 - 5 = 20 songs that were never released. So, Skyler wrote a total of 25 + 35 + 20 = 80 songs.
The answer: 80
What was the question?
Question: Skyler is a composer. He wrote 25 hit songs that made it on the top 10 charts; ten more songs that made it on the top 100 charts than the hit songs; 5 fewer songs than the hit songs that were never released. How many songs did Skyler write in all?


The second protest was 4 * .25 = 1 day longer than the first. So the second protest was 4 + 1 = 5 days. Thus he spent 4 + 5 = 9 days protesting.
The answer: 9
Reverse engineering the question: John attends a protest for 4 days. He then attends a second protest for 25% longer than the first. How many days did he spend protesting?


The taco truck sold 3 + 2 * 10 = 3 + 20 = 23 soft tacos. It made 2 * 23 = $46 from soft tacos. It made 5 * 4 = $20 from hard shell tacos. Thus, the taco truck made 46 + 20 = $66 during the lunch rush.
The answer: 66
Reverse engineering the question:

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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A taco truck is selling soft tacos for $2 and hard shell tacos for $5 during the lunch rush. The first group of customers is a family that buys four hard shell tacos and three soft tacos. The rest of the customers in the lunch rush only buy two soft tacos each. There were ten customers after the family. How many dollars did the taco truck make during the lunch rush?