Solution: Let a cylinder of water be "1"
Then there is the water at night: 1/2 unit is less 1 liter. That is, * * * uses: 1/2 more than 1 liter.
Then 20% of the daytime water consumption is: 1/2 units, 28 liters less.
So * * * water: 28/[ 1/2-20%]=280/3 liters.
2) There are two bookcases, and the number of books in the second bookcase is equivalent to 62.5% of that in the first bookcase. If you take out 15 books from the first bookcase and put them in the second bookcase, the number of books in the two bookcases will be equal. How many books are there in the first bookcase?
Solution: The first one is more than the second one: 15*2=30 copies.
The first original book: 30/[ 1-62. 5%]=80
3) One day, a young man came to Boss Wang's shop and bought a present. The cost of this gift is 18 yuan, and the list price is 2 1 yuan. As a result, the young man took out 100 yuan to buy this gift. Boss Wang had no change at that time, so he changed the 100 found in the neighborhood and gave it to the young man.
The question now is: How much did Boss Wang lose in this transaction?
A: 197 yuan.
79+ 100+3
It is 79 yuan who is looking for young people.
Accompany the neighborhood 100 yuan
The bonus fee is 18 yuan.
The total is 197 yuan.