When John gives his sister 1 / 4 of his money, he parts with 1 / 4 * 100 = 25 dollars. Johns remains with 100 - 25 = 75 dollars. When he buys groceries worth $40, he remains with 75 - 40 = 35 dollars.
The answer: 35
Reverse engineering the question: John receives $100 from his uncle and gives his sister Jenna 1/4 of that money. He goes and buys groceries worth $40. How much money does John have remaining?


Reasoning and answer: The students' entrance fee cost $5 x 35 = $175. The adults' entrance fee cost $6 x 4 = $24. Therefore, the school will pay a total of $175 + $24 = $199 for the farm entrance.
The answer: 199
What was the question?
Question: Jessica’s class is going to a farm for a field trip. The school will bring all 35 students in the class plus 4 adult chaperones. The farm entrance fee for students costs $5 and $6 for adults. How much will the school pay for the farm entrance in all?


Age 5 years ago: 17 - 5 = 12. Sister's age 5 years ago: 35 - 12 = 23. Sister's age today: 23 + 5 = 28 years. Djibo's sister is 28 years old today.
The answer: 28
Reverse engineering the question: Djibo is 17 years old. Five years ago Djibo added his age with his sister's age and the sum was 35. How many years old is Djibo's sister today?


Reasoning and answer: There are two walls that are 12' X 10' and two walls that are 16' by 10'. First find the size in square feet of one 12' x 10' wall by multiplying the height and length: 12 ft * 10 ft = 120 sq ft. Multiply that quantity by 2 since there are two 12' x 10' walls: 120 sq ft * 2 = 240 sq ft. Then find the size in square feet of one 16' x 10' wall by multiplying the height and length: 16 ft * 10 ft = 160 sq ft. Multiply that quantity by 2 since there are two 16' x 10' walls: 160 sq ft * 2 = 320 sq ft. Now add the square footage of both sets of walls to find the total square footage Martha needs to paint: 240 sq ft + 320 sq ft = 560 sq ft. Now multiply that amount by 3 because Martha needs to add 3 coats: 560 sq ft / coat * 3 coats = 1680 sq ft. Finally, divide the total square footage by Martha's painting rate to find how many hours she needs to finish: 1680 sq ft / 40 sq ft / hour = 42 hours.
The answer: 42
What was the question?
Question: Martha needs to paint all four walls in her 12 foot by 16 foot kitchen, which has 10 foot high ceilings. Each wall needs one coat of primer and two coats of paint. If Martha can paint 40 square feet per hour, how many hours will it take her to paint the kitchen?


26 / 2 = 13 of the purses are genuine. 24 / 4 = 6 of the handbags are fake. 24 - 6 = 18 of the handbags are genuine. There are 13 + 18 = 31 genuine purses and handbags.
The answer: 31
Reverse engineering the question: Tirzah has a lot of purses and handbags; in total she has 26 purses and 24 handbags. Half the purses and 1/4 the handbags are fake. If the rest are authentic, how many purses and handbags in total are genuine?


The original amount is $50 so half is $50 / 2 = $25. 4 students paid half ($25) for a total of 4 * $25 = $100. There are 25 - 4 = 21 students left. 21 students paid the full amount ($50) for a total of 21 * $50 = $1050. They were able to gather a total of $100 + $1050 = $1150.
The answer: 1150
Reverse engineering the question:
In Mary's class, there are 25 students. Their teacher told them they could pay $50 each to finance a big science project that they and their society would benefit greatly from. They all paid the full amount except for 4 students, who paid half. How much was the class able to gather together?