At the end of 2018, the tree will grow 100 x 10 / 100 = 10 meters more. Thus, its height at the end of 2018 is 100 + 10 = 110 meters. At the end of 2019, the tree will grow 110 x 10 / 100 = 11 meters more. So, its height at the end of 2019 is 110 + 11 = 121 meters. Therefore, the tree has grown 121 - 100 = 21 meters.
The answer: 21
Reverse engineering the question: A certain tree was 100 meters tall at the end of 2017. It will grow 10% more than its previous height each year. How long has the tree grown from 2017 until the end of 2019?


Reasoning and answer: Phil started with 50, and doubled this amount the next year for 50 * 2 = 100 coins. Phil then collected 3 per month the following year, and since there are 12 months in a year that was 3 * 12 = 36 coins added. Phil then collected 1 every third month, and since there are 12 months that means he collected one every 12 / 3 = 4 months, for 4 coins added. Before he lost a quarter of his coins, Phil had 100 + 36 + 4 coins, or 140 coins in total. Losing a quarter of 140 coins means Phill lost 140 / 4 = 35 coins. That means Phil had 140 - 35 = 105 coins remaining.
The answer: 105
What was the question?
Question: Phil has a coin collection he likes to add to. He started with 50 state quarters his parents gave him. Over the next year he doubled this. The following year he collected 3 each month. The year after that he collected 1 every third month. The year after that he lost a quarter of them when he misplaced his collection. How many did he have left after losing some?


Altogether, Jim has 200g + 100g + 100g = 400g of flour. He can therefore bake 400g / 200g = 2 loaves of bread.
The answer: 2
Reverse engineering the question: Jim is baking loaves of bread. He has 200g of flour in the cupboard, 100g of flour on the kitchen counter, and 100g in the pantry. If one loaf of bread requires 200g of flour, how many loaves can Jim bake?


Reasoning and answer: She uses 4 hours / day * 125 watts / hour = 500 watt hours / day. That means she uses 500 watt hours / day * 7 days / week = 3500 watt hours / week. This is 3500 watt hours / 1000 watts / kw = 3.5 kw hours. So her TV cost 3.5 kw hours / week * $0.14 / kw hour = $0.49 / week.
The answer: 49
What was the question?
Question: Kim's TV uses 125 watts of electricity per hour. She runs it for 4 hours a day. If electricity cost 14 cents per kw/h how many cents does her TV cost to run for a week?


The cost will for 3 adults will be $12 / adult x 3 adults = $36. The cost for 3 children will be $10 / child x 3 children = $30. The total cost will be $36 + $30 = $66.
The answer: 66
Reverse engineering the question: Julia is performing in her high school musical this weekend and her family wants to come to the show. Tickets are $12 for adults and $10 for children. If her mom, dad, grandma, and three little sisters come to the show, how much will the total be for their tickets?


Liza used 10 / 2 = 5 kilograms of butter for the chocolate chip cookies. Then, she used 10 / 5 = 2 kilograms of butter for the peanut butter cookies. She used 5 + 2 = 7 kilograms of butter for the chocolate and peanut butter cookies. So, only 10 - 7 = 3 kilograms of butter was left. Then, Liza used 3 / 3 = 1 kilograms of butter for the sugar cookies. Therefore, only 3 - 1 = 2 kilograms of butter were left.
The answer: 2
Reverse engineering the question:
Liza bought 10 kilograms of butter to make cookies. She used one-half of it for chocolate chip cookies, one-fifth of it for peanut butter cookies, and one-third of the remaining butter for sugar cookies. How many kilograms of butter are left after making those three kinds of cookies?