Logical problem of staying in a hotel for 5 yuan

Answer: The 9 yuan money spent by each person already includes the 2 yuan money hidden by the waiter (that is, the preferential price 25 yuan+the waiter owns 2 yuan =27 yuan =3*9 yuan). Therefore, when calculating the composition of 30 yuan, the 2 yuan money hidden by the waiter cannot be counted, but should be added with 1 yuan returned to everyone. That is 3*9+3* 1=30 yuan is just right! You can also think about it from another angle .. Those three people went out of 30 yuan and spent 25 yuan, and the waiter hid 2 yuan, so each person spent 9 yuan, plus the share of 1 yuan, which happened to be 30 yuan. So this dollar was found.

Summary: This puzzle is mainly because it separates 2 yuan money from 27 yuan money. The original algorithm mistakenly thought that the 2 yuan left by the waiter privately was not included in the 27 yuan, so the wrong result was 1 yuan. In fact, this 27 yuan includes 2 yuan left privately. Add the returned 3 yuan money, and the result happens to be 30 yuan.

Tired of typing, I hope to adopt it.