If there are 600 people at the fair this year, the number going to the fair next year is 2 * 600 = 1200. The number of people at the fair this year and the ones going next year totals 1200 + 600 = 1800. The number of people who went to that fair last year was 200 less than those going next year, meaning there were 1200 - 200 = 1000 people at the fair last year. In the three years, the number of people at the fair will be 1800 of this and next year + 1000 of last year = 2800.
The answer: 2800
Reverse engineering the question: Next year, there will be twice as many people going to the fair as are going this year, and the number of people who went to the fair last year was 200 less than those going next year. If the number of people going to the fair this year is 600, calculate the number of people at the fair in the three years.

There are 540 pounds / 30 pounds / crate = 18 crates of fish needed. Hence, the total cost for the shipment is $1.5 / crate x 18 crates = $27.
The answer: 27
Reverse engineering the question: Lizzy has to ship 540 pounds of fish that are packed into 30-pound crates. If the shipping cost of each crate is $1.5, how much will Lizzy pay for the shipment?

Jackson deleted all his old emails so now he only has the new ones left, which he first gets 15 + 5 of = 20 emails. Then Jackson receives 10 more emails to add to the other 20 new ones, 10 + 20 = 30 new emails.
The answer: 30
Reverse engineering the question: Jackson is clearing out his email inbox after noticing he has a whole lot of emails that he no longer needs and can delete. While he is cleaning his inbox, though, he keeps getting more emails. While he deletes 50 emails he gets another 15 sent to him. While he deletes 20 more he receives 5 more emails. After he is done deleting all his old emails he has just the new emails left, including 10 more that were sent to him. How many emails are there in Jackson's inbox now?

If the price of a lawnmower was $1800 a year ago, 2 / 5 less than the cost right now, then it now costs 2 / 5 * 1800 = $720 more to buy one lawnmower. The total cost of buying one lawnmower right now is $1800 + $720 = $2520. To purchase 4 such lawnmowers, Mr. Lucian will have to pay $2520 * 4 = $10080.
The answer: 10080
Reverse engineering the question:
A year ago, the total cost of buying a lawnmower was 2/5 times less than the cost it goes for now. If the cost was $1800 a year ago, calculate how much it would cost Mr. Lucian to buy 4 such lawnmowers.