Toby has 60 friends because 33 / .55 = 60. 45% of his friends are girls because 100 - 55 = 45. He has 27 friends who are girls because 60 x .45 = 27.
The answer: 27
Reverse engineering the question: 55% of Toby's friends are boys and the rest are girls. If he has 33 friends who are boys, how many friends does he have who are girls?


Reasoning and answer: For each liter of chlorine, I can save $10 x .20 = $2. For each box of soap, I can save $16 x .25 = $4. With the 3 liters of chlorine, I can save $2 x 3 = $6. With the 5 boxes of soap, I can save $4 x 5 = $20. Therefore, I can save a total of $6 + $20 = $26.
The answer: 26
What was the question?
Question: A liter of chlorine costs $10 and is now sold at 20% off. A box of soap that costs $16 is now sold at 25% off. How much will you save if you buy 3 liters of chlorine and 5 boxes of soap?


First find the total number of people by adding the number of passengers and flight crew: 30 people + 5 people = 35 people. Then find the total number of bags by doubling the total number of people: 35 people * 2 bags / person = 70 bags. Then find the fuel increase caused by the people by multiplying their number by the fuel increase per person: 35 people * 3 gallons / mile / person = 105 gallons / mile. Then multiply the number of bags by the fuel increase per bag to find the total fuel increase they cause: 70 bags * 2 gallons / mile / bag = 140 gallons / mile. Now add the fuel increases to the base fuel consumption to find the total fuel needed per mile: 140 gallons / mile + 105 gallons / mile + 20 gallons / mile = 265 gallons / mile. Now multiply the fuel consumption per mile by the number of miles flown to find the total amount of fuel needed: 265 gallons / mile * 400 miles = 106,000 gallons of fuel.
The answer: 106000
Reverse engineering the question: Carol is an aviation engineer deciding how much fuel to put in a jet. The empty plane needs 20 gallons of fuel per mile. Each person on the plane increases this amount by 3 gallons per mile, and each bag increases it by 2 gallons per mile. If there are 30 passengers and 5 flight crew, and each person brought two bags, how many gallons of fuel does the plane need for a 400-mile trip?


Reasoning and answer: Karen makes $3000 / (3 / 4) = $4000 per month. In three months, Karen would make a total of $4000 * 3 = $12000. To make the same amount of money John would need to work $12000 / $3000 = 4 months.
The answer: 4
What was the question?
Question: Jon makes 3/4's the salary that Karen makes. John makes $3000 per month. How long will it take him to make the same amount of money that Karen does in 3 months?


He bought 5 * 4 = 20 pounds of beef. So he paid 20 * 5.5 = $110.
The answer: 110
Reverse engineering the question: James buys 5 packs of beef that are 4 pounds each. The price of beef is $5.50 per pound. How much did he pay?


The Saturday morning exodus out of the park comprised 4 * 2880 = 11520 elephants. This means that after the exodus, the park was left with 30000 - 11520 = 18480 elephants. Since the final number of elephants was 28,980, the new elephants that entered were 28980 - 18480 = 10500. The rate at which the new elephants entered the park was therefore 10500 / 7 = 1500 elephants / hour.
The answer: 1500
Reverse engineering the question:
Utopia National Park hosted 30,000 elephants on Friday night. The next morning, there was a 4-hour elephant exodus out of the park, at a constant rate of 2,880 elephants/hour. Over the next 7-hour period, new elephants entered the park at a constant rate. If the final number of elephants in the park was 28,980, at what rate did the new elephants enter the park?