The marbles are divided into 4 + 5 = 9 parts. Each part consists 36 / 9 = 4 marbles. So Manny had 5 parts x 4 = 20 marbles. After giving 2 marbles to his brother, he now has 20 - 2 = 18 marbles left.
The answer: 18
Reverse engineering the question: Thirty-six marbles are divided between Mario and Manny in the ratio 4:5. If Manny decided to give 2 marbles to his brother, how many marbles does Manny have now?


Reasoning and answer: Janice can earn $30 x 5 = $150 per week. She will earn $15 x 3 = $45 more if she works three overtime shifts. Therefore, Janice will earn $150 + $45 = $195 this week.
The answer: 195
What was the question?
Question: Janice has been working part-time at a convenience store 5 days a week. She can earn $30 per day and can earn $15 more when she works a 2 hour overtime shift. If she works three overtime shifts this week, how much will she earn this week?


If the elder son is 40 years old now, the younger son is 40 - 10 = 30 years old. In 30 years from now, the younger son will be 30 + 30 = 60 years old.
The answer: 60
Reverse engineering the question: The difference in age between Declan's elder son and younger son is 10 years. If the elder son is 40 years old now, how old will the younger son be 30 years from now?


Reasoning and answer: We have 12 km / 3 km = 4. So, the distance covered in 12 km is 4 times greater than 3 km. The time taken will also be 4 times greater. So, 2 hours x 4 = 8 hours. We convert the time to minutes: 8 hours * 60 minutes / hour = 480 minutes.
The answer: 480
What was the question?
Question: To make 3 km, Ben walked for 2 hours. Continuing at the same speed, how much time in minutes would it take him to travel 12 km?


There are 12 cookies in 1 dozen, so in the morning, she sold 12 x 3 dozen = 36 cookies. Throughout the day, she sold 36 cookies in the morning + 57 cookies at lunch + 16 cookies in the afternoon = 109 cookies. She started with 120 cookies – 109 cookies sold = 11 cookies to take home.
The answer: 11
Reverse engineering the question: Katrina has 120 cookies to sell at her bakery. She plans to take home any cookies she doesn’t sell by the end of the day. In the morning, she sells 3 dozen cookies. During the lunch rush, she sells 57 cookies. In the afternoon, she sells 16 more cookies. How many cookies does she have left to take home?


First divide the download time in half to find the install time: 10 minutes / 2 = 5 minutes. Then add that amount of time to the download time: 5 minutes + 10 minutes = 15 minutes. Then triple that amount of time to find the tutorial time: 15 minutes * 3 = 45 minutes. Then add that time to the install and downtime time to find the total time: 45 minutes + 15 minutes = 60 minutes.
The answer: 60
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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James spends 10 minutes downloading a game, half as long installing it, and triple that combined amount of time going through the tutorial. How long does it take before he can play the main game?