There were 10 + 15 = 25 girls in the party. So, there were a total of 15 + 25 = 40 attendees. 40 x 2 = 80 cans of soft drinks are needed. So, Mary bought 80 / 8 = 10 boxes of soft drinks. Therefore, Mary spent 10 x $5 = $50 on soft drinks.
The answer: 50
Reverse engineering the question: There were 15 males and 10 more girls at the party. Each attendee received 2 cans of soft drinks. If Mary bought several boxes of soft drinks where a box contains 8 cans and is priced at $5 for each box, how much did Mary spend on soft drinks?


Reasoning and answer: 7 times the number of bats Randy has is 29 - 1 = 28. Randy has 28 / 7 = 4 bats.
The answer: 4
What was the question?
Question: Randy has 1 more baseball glove than 7 times the number of bats he has. If he has 29 baseball gloves, how many bats does he have?


First multiply Marla's one - way driving time by 2 to find her total driving time: 20 minutes * 2 = 40 minutes. Then add Marla's driving time to the time spent attending the conference to find the total time: 70 minutes + 40 minutes = 110 minutes.
The answer: 110
Reverse engineering the question: Marla has to spend 20 minutes driving one way to her son's school, then 70 minutes attending parent-teacher night, then the same amount of time driving home. How many minutes does Marla spend on this errand in total?


Reasoning and answer: Mary got 1 * 12 = 12 books from the book club. She bought 5 + 2 = 7 books. She was given 1 + 4 = 5 books. She got rid of 12 + 3 = 15 books. Thus, at the end of the year she had 72 + 12 + 7 + 5 - 15 = 81 books.
The answer: 81
What was the question?
Question: Mary has a mystery book library. She started with 72 mystery books at the beginning of the year. She joined a book club that sent her 1 book each month of the year. She went to a bookstore halfway through the year and bought 5 more books, then bought 2 books at yard sales later. Her daughter gave her another book for her birthday, and her mother gave her a series of 4 books when Mary visited her. She donated 12 books she didn't want to read again to a charity shop and sold 3 to a used book store. How many books did she have at the end of the year?


First find the area of the lot by multiplying the width and the length: 120 ft * 60 ft = 7200 sq ft. Then find the area of the square covered in concrete: 40 ft * 40 ft = 1600 sq ft. Then subtract the concrete area from the total area to find the grassy area: 7200 sq ft - 1600 sq ft = 5600 sq ft. Finally, divide this area by the area each bag covers to find the number of bags: 5600 sq ft / 56 sq ft / bag = 100 bags.
The answer: 100
Reverse engineering the question: Amanda is figuring out how many bags of grass seed she needs to buy to cover a new lot the city is turning into a park. The lot measures 120 feet by 60 feet. One section that measures 40 feet by 40 feet will be covered with concrete, and the rest needs to be covered in grass seeds. Each bag of grass seeds covers 56 square feet. How many bags of grass seeds does Amanda need?


The ping pong balls cost 10000 * .10 = $1000. So the discount is 1000 * .30 = $300. So he pays 1000 - 300 = $700.
The answer: 700
Reverse engineering the question:
Ping pong balls sell for $.10 each. Johnny buys 10000 for a prank. He gets a 30% discount for buying in such large bulk. How much does he pay?