Combining the three classes, there are 17 + 14 + 15 = 46 male students. Similarly, there are 13 + 18 + 17 = 48 female students. Thus, there are 48 - 46 = 2 students who cannot partner with a student of the opposite gender.
The answer: 2
Reverse engineering the question: Three different 6th grade classes are combining for a square dancing unit. If possible, the teachers would like each male student to partner with a female student for the unit. The first class has 17 males and 13 females, while the second class has 14 males and 18 females, and the third class has 15 males and 17 females. When the classes are combined, how many students will be unable to partner with a student of the opposite gender?

Carlos read 28 books + 30 books = 58 books. He needed to read 100 books - 58 books = 42 books in June.
The answer: 42
Reverse engineering the question: Carlos read 28 books in July and 30 books in August. He needed to read 100 books during his summer vacation. If Carlos read some of the books in June, calculate the number of books that Carlos read in June to meet his goal?

The bananas cost 4 x $1 = $4. The apples cost 3 x $2 = $6. The strawberries cost (24 / 12) x $4 = $8. The avocados cost 2 x $3 = $6. The grapes cost 2 x $2 = $4. The total cost of the fruit basket is $4 + $6 + $8 + $6 + $4 = $28.
The answer: 28
Reverse engineering the question: A fruit basket consists of 4 bananas, 3 apples, 24 strawberries, 2 avocados, and a bunch of grapes. One banana costs $1. An apple costs $2. 12 strawberries cost $4. An avocado costs $3, and half a bunch of grapes costs $2. What is the total cost of the fruit basket?

He wants to serve 5 hushpuppies to each guest and he is having 20 guests so that's 5 * 20 = 100 hush puppies. He can only cook 10 hushpuppies at a time and he needs to cook 100 hushpuppies so that's 100 / 10 = 10 batches of hushpuppies. Each batch takes 8 minutes to cook and he has 10 batches to cook so it will take him 8 * 10 = 80 minutes.
The answer: 80
Reverse engineering the question:
Walter wants to serve hushpuppies to his guests for his annual fish fry event. He thinks each guest will eat 5 hushpuppies and he is having 20 guests. He can cook 10 hushpuppies in 8 minutes. How long will it take to cook all of the hushpuppies?