50cm³ will make one balloon touch the ceiling so 1800cm³ will make 1800 / 50 = 36 balloons touch the ceiling. There are 50 balloons in total so 50 - 36 = 14 balloons will not float since they were filled with ordinary air. There are 36 - 14 = 22 more balloons touching the ceiling than not.
The answer: 22
Reverse engineering the question: While preparing balloons for Eva's birthday party, her mom bought 50 balloons and 1800cm³ of helium. One balloon needs 50cm³ to float high enough to touch the ceiling, and she can fill any remaining balloon with ordinary air. If she used up all of the helium and inflated every balloon, how many more balloons are touching the ceiling than not?


Reasoning and answer: She found 10 quarters that are $0.25 each so she found 10 * .25 = $2.50. She found 3 dimes that are $0.10 each so she found 3 * .10 = $0.30. She found 3 nickels that are $0.05 each so she found 3 * .05 = $0.15. She found 5 pennies that are $0.01 each so she found 5 * .01 = $0.05. All total she found 2.50 + .30 + .15 + .05 = $3.00 in change.
The answer: 3
What was the question?
Question: When Harriett vacuumed the sofa and chair she found 10 quarters, 3 dimes, 3 nickels, and 5 pennies. How much money did Harriett find?


The toppings on each pizza are $6 because 3 x 2 = 6. The total for each pizza is $20 because 14 + 6 = 20. The pizzas cost $40 because 2 x 20 = 40. The tip is $10 because 40 x .25 = 10. The total is $50 because 40 + 10 = 50.
The answer: 50
Reverse engineering the question: Harry is ordering pizza. A large pizza is 14. It costs $2 per topping. He orders 2 large pizzas, each with 3 toppings. He then adds a 25% tip. What is the total cost?


Reasoning and answer: There are 60 minutes in an hour, so the trip took 1 1 / 2 * 60 = 90 minutes. Josie spent 3 + 13 + 14 + 18 = 48 minutes waiting. Thus, she spent 90 - 48 = 42 minutes shopping.
The answer: 42
What was the question?
Question: On a shopping trip in a crowded store, Josie had to wait 3 minutes for a cart, 13 minutes for an employee to unlock a cabinet to get her a product, 14 minutes for a stocker to restock a shelf with what she wanted, and 18 minutes in line to check out. Her shopping trip took an hour and a half. How many minutes did Josie spend shopping instead of waiting?


If Sid attended four times as many college courses as Max, he attended 4 * 40 = 160 college courses. The total of college courses they both attended is 160 + 40 = 200.
The answer: 200
Reverse engineering the question: Max attended 40 college courses in 2 years. Sid attended four times as many college courses as Max in the same period. What's the total of college courses they both attended?


First, find how many servings one corn plant produces by multiplying the number of carrot servings by 5: 4 servings * 5 = 20 servings. Then find how many servings one green bean plant produces by dividing the number of corn servings by two: 20 servings / 2 = 10 servings. Now multiply the number of servings per carrot plant by the number of carrot plants: 4 servings / plant * 9 plants = 36 servings. Do the same for corn: 20 servings / plant * 9 plants = 180 servings. And do the same for green beans: 10 servings / plant * 9 plants = 90 servings. Now add up the servings for all three types of plant: 36 servings + 180 servings + 90 servings = 306 servings.
The answer: 306
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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Jimmy is setting up a garden. He has three plots: one plot for green beans, one plot for carrots, and one plot for corn. Each corn plant produces 5 times as many servings of veggies as each carrot, and each green bean plant produces half as many servings as each corn plant. If each carrot produces 4 servings of vegetables, and each plot has 9 plants, how many servings of vegetables is Jimmy growing?