Aiguo = 20 shells. Vail = 20 - 5 = 15 shells. Stefan = 15 + 16 = 31 shells. Total = 20 + 15 + 31 = 66. The 3 children had 66 seashells altogether.
The answer: 66
Reverse engineering the question: Stefan, Vail, and Aiguo collected seashells. Stefan had 16 more seashells than Vail. Vail had 5 less than Aiguo. Aiguo had 20 seashells. How many seashells did the 3 children have in total?


Reasoning and answer: Since there was a 10% discount, this means that Solomon only paid 100% - 10% = 90% of the original price. The 90% is represented by $450, so 1% is equal to $450 / 90 = $5. Therefore, the original price of the dining table is $5 x 100 = $500.
The answer: 500
What was the question?
Question: Solomon bought a dining table at a 10% discount and paid the sale price of $450. What was the original price of the dining table?


Since there are 60 minutes in 1 hour, then Lisa walks for 1 x 60 = 60 minutes every day. For 60 minutes, Lisa walks 60 x 10 = 600 meters. Thus, she walks for 600 x 2 = 1200 meters in two days.
The answer: 1200
Reverse engineering the question: Lisa walks 10 meters each minute. Every day, she walks for an hour. How many meters will Lisa walk in two days?


Reasoning and answer: The supplies for every student will cost 5 + 2 + 1 = $8. The supplies for the whole class will cost 8 * 23 = $184 in total.
The answer: 184
What was the question?
Question: A teacher has to order supplies for his class to do a science project. Each student needs a bow, a small bottle of vinegar and a box of baking soda. Bows are $5 each, a bottle of vinegar is $2 and a box of baking soda is $1. The teacher has 23 students in this class. How much will the supplies cost?


Currently, the farm has 2 + 3 + 6 = 11 animals. The farmer will add 3 + 5 + 2 = 10 animals. So, the farm will have 11 + 10 = 21 animals.
The answer: 21
Reverse engineering the question: On a farm, there are 2 cows, 3 pigs, and 6 goats. The farmer planned on adding 3 cows, 5 pigs, and 2 goats. How many animals will there be on the farm?


Let X be the age of the older friend. The younger friend is X - 2 years old. So, the age of both is X + (X - 2) = 74. X + X = 74 + 2. 2 * X = 76. Then, the older friend is X = 38 years old.
The answer: 38
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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The difference between the ages of two friends is 2 years. The sum of their ages is 74 years. Find the age of the older friend.