First find the total Janet spends on clarinet lessons per week: $40 / hour * 3 hours / week = $120 / week. Then find the total Janet spends on piano lessons per week: $28 / hour * 5 hours / week = $140 / week. Then subtract her weekly clarinet spending from her weekly piano spending to find the weekly difference: $140 / week - $120 / week = $20 / week. Then multiply the weekly difference by the number of weeks in a year to find the annual difference: $20 / week * 52 weeks / year = $1040 / year.
The answer: 1040
Reverse engineering the question: Janet pays $40/hour for 3 hours per week of clarinet lessons and $28/hour for 5 hours a week of piano lessons. How much more does she spend on piano lessons than clarinet lessons in a year?

Woody needs to save another $282 - $42 = $240 to be able to afford a games console. It will take Woody $240 / $24 / week = 10 weeks to save up enough money.
The answer: 10
Reverse engineering the question: Woody wants to buy a games console that costs $282. Woody already has $42 and receives an allowance of $24 every week. How many weeks will it take him to save the money he needs for the game console?

Let c be the number of cucumbers and t the number of tomatoes. The total is the sum of the number of cucumbers and that of tomatoes, which is c + t = 280 piece of vegetables. Since there are thrice as many tomatoes as cucumbers, this means c = t / 3. Therefore 3 * c = t. The sum will therefore be c + 3 * c = 280 pieces of vegetables. This means that 4 * c = 280 vegetables. Therefore c = 280 / 4 = 70 cucumbers.
The answer: 70
Reverse engineering the question: Barry wants to make a huge salad using only cucumbers and tomatoes. He will use a total of 280 pieces of vegetables. If there are thrice as many tomatoes as cucumbers, how many cucumbers will be used in the salad?

The total cost of the iPhone will cost Carrie $800 - $240 = $560. It will take her $560 / $80 = 7 weeks to earn enough money.
The answer: 7
Reverse engineering the question:
Carrie wants to buy a new iPhone. The new iPhone costs $800. She can trade in her Samsung Galaxy for $240. She can make $80 per week babysitting. How many weeks does she have to work before she can purchase the iPhone?