The amount of the discount is 20 / 100 * $90 original price = $18. Charlotte needs to bring the $90 - $18 discount = $72.
The answer: 72
Reverse engineering the question: Charlotte needs to know how much money to have with her when she goes to the shoe store. How much money should Charlotte bring to buy a pair of boots, if the original price is $90 and there is a discount of 20%?


Reasoning and answer: In the first verse, 30 / 2 = 15 singers sang. In the second verse, 15 / 3 = 5 singers joined in. In the final verse, 30 - 15 - 5 = 10 singers joined for the whole choir to sing together.
The answer: 10
What was the question?
Question: A choir was singing a song that involved 30 singers. In the first verse, only half of them sang. In the second verse, a third of the remaining singers joined in. How many people joined in the final third verse that the whole choir sang together?


To get the perimeter, you add all the sides o the triangles, so the first two sides add up to 40 + 50 = 90 cm. If the perimeter of the triangle is 160, the remaining side is 160 - 90 = 70 cm.
The answer: 70
Reverse engineering the question: The perimeter of a triangle is 160 cm. If two of the sides are 40 cm and 50 cm, calculate the length of the third side?


Reasoning and answer: Traveling 20 hours due east at 30 kilometers per hour, the ship sailed 20 * 30 = 600 kilometers the first day. If half the distance to the destination is 600 kilometers, then 2 * 600 = 1200 kilometers is the total distance from start to destination. One - third of the distance from start to destination is 1 / 3 * 1200 = 400 kilometers. Thus, the wind storm blew the ship in a westward direction for 600 - 400 = 200 kilometers.
The answer: 200
What was the question?
Question: On the first day of the journey, the Skipper sailed his ship halfway to the destination by traveling due east for 20 hours at a speed of 30 kilometers per hour, and then turned the ship's engines off to let them cool down. But while the engines were off, a wind storm blew his vessel backward in a westward direction. After the storm, the Skipper used his GPS device to determine the new location of the ship, and he discovered that he was only one-third of the way to his destination. How many kilometers had the ship been blown in a westward direction by the storm?


The price of one performance is 3 * $5 = $15. Mark intends to go to the theater once a week, so in 9 weeks he will spend 6 * $15 = $90.
The answer: 90
Reverse engineering the question: Mark loves to see shows in theaters. He decided to visit the theater at least once a week. One performance lasts 3 hours. The price of the ticket depends on the time spent in the theater and stands at $5 for each hour. How much will Mark spend on visits to the theater in 6 weeks?


Last week = 111 texts. This week = (2 * 111) - 50 = 172 texts. 111 + 172 = 283 texts. Keiko sent 283 texts last week and this week combined.
The answer: 283
Reverse engineering the question:
Keiko sent 111 text messages last week. This week she sent 50 less than double what she sent last week. How many text messages did Keiko send last week and this week combined?