Let the number of days be x. He saves $50 - $15 = $35 each day. After x days he had saved $35 * x = $35x. His mom doubled his savings to give $35x * 2 = $70x. His dad added $10 to give $70x + $10 = $500. Subtracting 10 from both sides of the equation formed gives $70x = 490. Dividing both sides by $70 give x = 7 days.
The answer: 7
Reverse engineering the question: Ben starts each day with $50, spends $15 every day and saves the rest. After a few days, his mom doubled his total savings and his dad gave him an additional $10. If he now has $500, How many days have elapsed?

If the sum of their ages is 140, and Asaf is 50 years old, Alexander is 140 - 50 = 90 years old. The age difference between Asaf and Alexander's age is 90 - 50 = 40. Since the age difference between Asaf and Alexander's age is half the total number of pencils Asaf has, Asaf has 2 * 40 = 80 pencils. If Alexander has 60 more pencils than Asaf, Alexander has 80 + 60 = 140 pencils. Together, they have 140 + 80 = 220 pencils.
The answer: 220
Reverse engineering the question: The age difference between Asaf and Alexander's age is half the total number of pencils Asaf has. The sum of their ages is 140, and Asaf is 50 years old. If Alexander has 60 more pencils than Asaf, calculate the total number of pencils they have together.

Tony got twice $1750 which is 2 * $1750 = $3500. The total amount shared was $1750 + $3500 = $5250.
The answer: 5250
Reverse engineering the question: Mr. Sam shared a certain amount of money between his two sons, Ken and Tony. If Ken got $1750, and Tony got twice as much as Ken, how much was the money shared?

First add the number of snowballs each person made to find the total: 50 snowballs + 150 snowballs = 200 snowballs. Then divide the number Janet made by the total number and multiply by 100% to express the answer as a percentage: 50 snowballs / 200 snowballs * 100% = 25%.
The answer: 25
Reverse engineering the question:
Janet makes 50 snowballs and her brother makes 150 snowballs. What percentage of the snowballs did Janet make?