Reasoning and answer: He returned 200 * .8 = 160 people. So he had 200 - 160 = 40 people. He took 10 of those to another planet so he took 40 - 10 = 30 to his home planet.
The answer: 30
What was the question?
Question: An alien invades Earth. It abducts 200 people. He returns 80% of the people abducted. After that he takes 10 people to another planet. He took the rest to his home planet. How many people did he take to his home planet?


Kelsey turned 25 in 1999 so she was born in 1999 - 25 = 1974. Kelsey's sister is older by 3 years so she was born in 1974 - 3 = 1971. It's currently 2021 and Kelsey's sister was born in 1971 so she is 2021 - 1971 = 50 years old.
The answer: 50
Reverse engineering the question: Kelsey turned 25 in 1999. Her older sister was born 3 years before Kelsey. It's currently 2021. How old is Kelsey's older sister?


Reasoning and answer: There are 10 x 3 = 30 green chairs. The total number of blue and green chairs is 10 + 30 = 40. So, there are 40 - 13 = 27 white chairs. Therefore, there are 40 + 27 = 67 chairs in a classroom.
The answer: 67
What was the question?
Question: In a classroom, there are blue chairs, green chairs, and white chairs. There are 10 blue chairs. The green chairs are 3 times as many as the blue chairs, and there are 13 fewer white chairs than the green and blue chairs combined. How many chairs are there in a classroom?


Matias sold 7 * 3 = 21 books on Wednesday, as he sold three times more books than on Tuesday. The sales from Wednesday were tripled on Thursday, which means Matias sold then 21 * 3 = 63 books. That means in total Matias sold 7 + 21 + 63 = 91 books during these three days.
The answer: 91
Reverse engineering the question: Matias is a salesman in a bookstore. He sold 7 books on Tuesday and three times as many on Wednesday. If the sales from Wednesday were tripled on Thursday, how many books did Matias sell during these three days combined?


Reasoning and answer: First find how many months Jason worked as a bartender: 9 years * 12 months / year = 108 months. Then find how many months Jason worked as a manager: 3 years * 12 months / year + 6 months = 42 months. Then add those two amounts to find his total amount of work experience: 108 months + 42 months = 150 months.
The answer: 150
What was the question?
Question: Jason worked for 9 years as a bartender and 3 years and six months as a manager. How many months of work experience does he have total?


Reasoning and answer: First find the total number of baby minks: 30 minks * 6 babies / mink = 180 minks. Add this to the number of adult minks: 180 minks + 30 minks = 210 minks. Then divide this number in half to find how many aren't set free: 210 minks / 2 = 105 minks. Then divide the remaining number of minks by the number of minks per coat to find the number of coats: 105 minks / 15 minks / coat = 7 coats.
The answer: 7
What was the question?
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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It takes 15 mink skins to make a coat. Andy buys 30 minks and each mink has 6 babies, but half the total minks are set free by activists. How many coats can he make?