Reasoning and answer: Cara's mom: 75 - 15 = 60 years old. Cara: 60 - 20 = 40 years old.
The answer: 40
What was the question?
Question: Cara is at her family reunion, where she discovers that she is 20 years younger than her mom. Her mom is 15 years younger than Cara's Grandmother. If Cara's grandmother is 75, how old is Cara?


The total number of towers at Mark's beach is 20 * 10 = 200 towers. There are 200 + 20 = 220 sandcastles and towers on Mark's beach. Jeff's beach has 3 * 20 = 60 sandcastles, three times as many as the number of sandcastles in Mark's beach. The number of towers in each of the sandcastles on Jeff's beach is 1 / 2 * 10 = 5. Since each sandcastle has 5 towers on Jeff's beach, there are 5 * 60 = 300 towers. In total, on Jeff's beach, there are 300 + 60 = 360 towers and sandcastles. Altogether, 360 + 220 = 580 sandcastles and towers can be found on their beaches.
The answer: 580
Reverse engineering the question: There are 20 sandcastles on Mark's beach, each with 10 towers. On Jeff's beach, there are three times as many castles as on Mark's beach, each with 5 towers. What is the combined total number of sandcastles and towers on Mark's and Jeff's beaches?


Reasoning and answer: Before going on vacation, Grandpa counts 36 tomatoes. After going on vacation, Grandpa has 100 * 36 = 3600 tomatoes. So in his absence, 3600 - 36 = 3564 tomatoes have grown.
The answer: 3564
What was the question?
Question: In his garden, Grandpa had counted 36 small tomatoes before going on vacation. When he came back from vacation, he counted 100 times more tomatoes. How many tomatoes grew in his absence?


After one year it earns $10 in interest because 100 x .1 = 10. It has $120 in it after a year because 100 + 10 + 10 = 120. In the second year it earns $12 in interest because 120 x .1 = 12. In the second year it has $142 in it because 120 + 12 + 10 = 142.
The answer: 142
Reverse engineering the question: Steve has a bank account that earns 10% interest every year. He puts $100 in it, and then 10 each year. How much money is in it after two years?


Reasoning and answer: On day two, she read 63 * 2 = 126 pages. On day three, she read 126 + 10 = 136 pages. On day four, she read 354 - 63 - 126 - 136 = 29 pages to finish the book.
The answer: 29
What was the question?
Question: Hallie borrows a book from the library. She reads the entire book in four days. She read 63 pages the first day. On the second day, she read twice the number of pages that she'd read on day one. On the third day, she read 10 mores pages than she read on day two. If the book is 354 pages long, how many pages did she read on the fourth day?


Reasoning and answer: At the end of Monday, there are 336 - 124 = 212 books left. At the end of Tuesday, there are 212 + 22 = 234 books.
The answer: 234
What was the question?
Question:
There are 336 books in a library. On Monday, 124 books are taken out. On Tuesday, 22 books are brought back. How many books are there now?