Let C be the number of lion cubs. There are 2C meerkats in the new exhibit. The zoo sent 4 gorillas away, so they had 68 - 6 = 62 animals left. They adopted a hippopotamus, so they had 62 + 1 = 63 animals. They took in 3 rhinos, so they had 63 + 3 = 66 animals. Thus, they had 90 - 66 = 24 new lion cubs and meerkats. Therefore, they had C + 2C = 3C = 24 new lion cubs as meerkats. Hence, there were C = 24 / 3 = 8 lion cubs born.
The answer: 8
Reverse engineering the question: A small zoo houses a variety of 68 wild animals. After they send a gorilla family of six to a different zoo, they adopt a hippopotamus from another zoo. A while later, an animal rescue contacted them, and the zoo took in three endangered rhinos. Then one of their lionesses gave birth to cubs, and they opened a meerkat exhibit with twice as many meerkats as they had gained lion cubs. The zoo then had 90 animals in all. How many lion cubs were born at the zoo?


Reasoning and answer: Jess needs to walk 11 blocks + 6 blocks + 8 blocks = 25 blocks total. Jess needs to go 25 blocks – 5 = 20 blocks to get to work.
The answer: 20
What was the question?
Question: Before getting to work, Jess has a few errands to run. Jess has to walk 11 blocks to the store and 6 blocks to the gallery, before walking the final 8 blocks to arrive at work. If Jess has already walked 5 blocks, how many more blocks must she walk before arriving at work?


On the first day, Cleo and Ignacio took 3 / 5 * 30 marbles = 18 marbles from the jar. When they shared the marbles, each got 18 marbles / 2 people = 9 marbles / person. The total number of marbles remaining in the jar is 30 marbles - 18 marbles = 12 marbles. On the third day, Cleo took 1 / 2 * 12 marbles = 6 marbles from the jar. The total number of marbles she has on the third day is 6 marbles + 9 marbles = 15 marbles.
The answer: 15
Reverse engineering the question: Cleo and Ignacio placed 30 of their marbles in a jar on a Monday. They took 3/5 of the marbles from the jar the next day and divided them equally. On the third day, Cleo took 1/2 of the marbles remaining in the jars. How many marbles did Cleo have on the third day?


Reasoning and answer: First find how many eggs per minute the owner can clean up: 60 seconds / minute / 15 seconds / egg = 4 eggs / minute. Then divide the total number of eggs by the number of eggs cleaned per minute to find how long the owner spends cleaning them up: 60 eggs / 4 eggs / minute = 15 minutes. Then find the total time the owner spends cleaning up toilet paper: 7 rolls * 30 minutes / roll = 210 minutes. Finally, add that amount to the egg cleaning time to find the total cleaning time: 210 minutes + 15 minutes = 225 minutes.
The answer: 225
What was the question?
Question: Every Halloween one house in the neighborhood gives out toothbrushes instead of candy, so it always gets egged and covered in toilet paper. If the owner spends 15 seconds cleaning up each egg and 30 minutes cleaning up each roll of toilet paper, how long (in minutes) will they have to spend cleaning up 60 eggs and 7 rolls of toilet paper?


Dr. Jones pays $6000 / 4 = $ 1500 for his electric and water bill. He pays $6000 / 5 = $1200 for his insurances. The total amount he pays for the bills and insurances is $1500 + $1200 = $2700. The remaining money from his earning after paying off the bills and insurance is $6000 - $2700 = $3300. The total amount he needs to pay for the rent and food expenses is $640 + $380 = $1020. So, Dr. Jones has $3300 - $1020 = $2280 left.
The answer: 2280
Reverse engineering the question: Dr. Jones earns $6,000 a month. His house rental is $640 each month; his monthly food expense is $380; his electric and water bill costs 1/4 of what he makes, and his insurances cost 1/5 of what he makes. How much money does he have left after paying those four bills?


Each day it needs to consume 7 / 7 = 1 gallon of blood. There are 128 / 16 = 8 pints per gallon. So he needs to suck blood from 8 / 2 = 4 people per day.
The answer: 4
Reverse engineering the question:
A vampire needs to suck 7 gallons of blood per week to survive. If he sucks 2 pints of blood per person, how many people does he need to suck each day to survive?