The store made a $50 x 30 / 100 = $15 profit for selling it 30% above the cost. So, the book was sold for $50 + $15 = $65. During a sale, the book's selling price decreased by $65 x 10 / 100 = $6.50. So, the book was sold for $65 - $6.50 = $58.50. There was $58.50 - $50 = $8.50 profit after the discount. Therefore, the percent profit is $8.50 / $50 x 100% = 17%.
The answer: 17
Reverse engineering the question: A store marks a book 30% above the cost. But during a sale, a 10% discount was given. If the book costs $50, what is the percent profit?
Reasoning and answer: Twice the money of Darwin is 2 * $45 = $90. The money that Mia have is $20 + $90 = $110.
The answer: 110
What was the question?
Question: Mia has $20 more than twice as much money Darwin has. If Darwin has $45, how much money does Mia have?
If the number of salmons in the river increased by ten times the number initially there, then 500 * 10 = 5000 new salmons migrated up the river. The total number of salmon in the river now is 5000 + 500 = 5500.
The answer: 5500
Reverse engineering the question: Because of the migration of salmon, the total number of salmon in river Trout has increased by ten times the number initially in the river. If there were 500 salmons initially, calculate the total number of fish in the river now.
Reasoning and answer: Lena = 3.5 hours = 210 minutes. Brother = 210 + 17 = 227 minutes. 210 + 227 = 437 minutes. Together, Lena and her brother played 437 minutes of video games.
The answer: 437
What was the question?
Question: Lena played video games for 3.5 hours last weekend. Her brother played 17 minutes more than she did. How many minutes together did Lena and her brother play video games last weekend?
There were 30 * .5 = 15 ounces of unburnt steak. So he ate 15 * .8 = 12 ounces of steak.
The answer: 12
Reverse engineering the question: John's grill messes up and burns half his steak. He eats 80% of what isn't burned. If the steak was originally 30 ounces how much steak did he eat?
If there are 30 notebooks on the shelf, there are 50 + 30 = 80 pens on the shelf. Altogether, Wesley has 80 + 30 = 110 notebooks and pens on the shelf.
The answer: 110
Reverse engineering the question:
There are 50 more pens than notebooks on Wesley's school library shelf. If there are 30 notebooks on the shelf, how many notebooks and pens, does he have altogether?