Half the pet - owners have a cat because 1 - 1 / 2 = 1 / 2. There are 60 pet owners because 30 / (1 / 2) = 60. The town has 100 citizens because 60 / .6 = 100.
The answer: 100
Reverse engineering the question: In a town where 60% of the citizens own a pet, half own a dog and 30 own a cat. How many citizens are in the town?
Reasoning and answer: The carpenter made 10 - 3 = 7 tables last month. So, the carpenter made 10 + 7 = 17 tables in all.
The answer: 17
What was the question?
Question: A carpenter made ten tables for this month. Last month, he made three fewer tables than this month. How many tables did the carpenter make in total?
The sports channels cost $12 - $3 = $9 per month. Jessica has to pay $15 + $12 + $9 = $36 in total per month.
The answer: 36
Reverse engineering the question: Jessica has a basic cable television service for $15 per month. If she adds the movie channels, it will cost an additional $12 per month. The sports channels cost $3 less per month than the movie channels. If Jessica adds the movie channels and the sports channels, what will her total monthly payment be?
Reasoning and answer: When Bella buys 2 / 5 times more marbles, she'll have increased the number of marbles by 2 / 5 * 60 = 24. The total number of marbles she'll have is 60 + 24 = 84. If Bella currently has 60 marbles, and she has two times as many marbles as frisbees, she has 60 / 2 = 30 frisbees. If Bella buys 2 / 5 times more frisbees, she'll have 2 / 5 * 30 = 12 more frisbees. The total number of frisbees she'll have will increase to 30 + 12 = 42. Bella also has 20 more frisbees than deck cards, meaning she has 30 - 20 = 10 deck cards. If she buys 2 / 5 times more deck cards, she'll have 2 / 5 * 10 = 4 more deck cards. The total number of deck cards she'll have is 10 + 4 = 14. Together, Bella will have a total of 14 + 42 + 84 = 140 items.
The answer: 140
What was the question?
Question: Bella has two times as many marbles as frisbees. She also has 20 more frisbees than deck cards. If she buys 2/5 times more of each item, what would be the total number of the items she will have if she currently has 60 marbles?
Store A has a $125 x 8 / 100 = $10 discount. So the smartphone from store A will only cost $125 - $10 = $115. Store B has a $130 x 10 / 100 = $13 discount. So the smartphone from store B will only cost $130 - $13 = $117. Thus, store A's smartphone is $117 - $115 = $2 cheaper than that of store B.
The answer: 2
Reverse engineering the question: Two stores sell the same model of smartphone, but they offer it at different prices and with different discounts. Store A lists the smartphone at a full price of $125 and offers an additional discount of 8%. Store B lists the same smartphone for $130 and offers an additional discount of 10%. After both stores' discounts are applied, how much cheaper is store A's smartphone than store B's smartphone?
There are 25 - 5 = 20 layers of rock that are not limestone. Half of those 20 are sandstone, so there are 20 / 2 = 10 that are not limestone or sandstone. Four of those are quartz, so 10 - 4 = 6 layers are not limestone, sandstone, or quartz. Half of the rest are shale, so 6 / 2 = 3 kinds of rock remain that make up only one layer in the strata.
The answer: 3
Reverse engineering the question:
There are 25 different layers of rock in a canyon's strata. Five of the layers are limestone. Half of the rest are sandstone. Four of the remaining are quartz. Half of the rest are shale. The rest are all different kinds of rock. How many kinds of rock make up only one layer in the canyon's strata?