Out of the 150 students, 100% - 60% = 40% are boys. So, there are 150 x 40 / 100 = 60 boys. Out of the 60 boys, 60 x 1 / 3 = 20 joined varsity clubs. Therefore, 60 - 20 = 40 boys did not join varsity clubs.
The answer: 40
Reverse engineering the question: Out of the 150 students, 60% are girls and the rest are boys. Only 1/3 of the boys joined varsity clubs. How many of the boys did not join varsity clubs?


Reasoning and answer: The break occurred (12 - 2) / 2 = 5 feet from the top. Then it was 12 - 5 = 7 feet from the base.
The answer: 7
What was the question?
Question: A flagpole is 12 feet tall. It breaks, folding over in half, such that what was the tip of the flagpole is now dangling two feet above the ground. How far from the base, in feet, did the flagpole break?


The pool is 10 * 6 * 20 = 1200 cubic feet. That means it is 25 * 1200 = 30000 liters. So it cost 3 * 30,000 = $90,000.
The answer: 90000
Reverse engineering the question: John is an eccentric millionaire. He decides to fill his swimming pool with bottled water. A cubic foot of water is 25 liters. His pool is 10 feet deep and 6 feet by 20 feet. A liter of water costs $3. How much does it cost to fill the pool?


Reasoning and answer: After keeping 10 cookies for herself, Karen has 50 - 10 = 40 cookies. After giving cookies to her grandparents, Karen has 40 - 8 = 32 cookies. Karen can give each person in her class 32 / 16 = 2 cookies.
The answer: 2
What was the question?
Question: Karen bakes 50 chocolate chip cookies. She keeps 10 for herself, and she gives 8 to her grandparents. If Karen wants to give everyone in her class cookies, and there are 16 people in her class, how many cookies will each person receive?


An additional three - quarters of 12cm is needed which is 12cm * (3 / 4) = 9cm. The total length required is 12cm + 9cm = 21cm.
The answer: 21
Reverse engineering the question: Roland needs a length of thread to complete an exercise. He has a 12cm long thread but his teacher says he needs an additional three-quarters of what he has. What is the total length required?


Ludwig earns a total of $10 x 4 = $40 from Monday to Thursday. He earns $10 / 2 = $5 per day on Friday, Saturday, and Sunday. So, his total salary for Friday, Saturday, Sunday is $5 x 3 = $15. Therefore, his total weekly salary is $40 + $15 = $55.
The answer: 55
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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Ludwig works 7 days a week and he usually works half of the day during Friday, Saturday, and Sunday. If his daily salary is $10, how much does he earn every week?