A very, very difficult math problem

Three kinds. From the inscription, it can be seen that the number of people in each room can only be , and each room cannot be 2 or 1 person.

Let's make a hypothesis first, assuming that there are two rooms with one person, then the third room has three people, which does not match the title, and is discarded.

Suppose there is one person in one room, then the other two rooms can only have 2 people each, which is the only answer that fits the question.

The number of people in the three rooms can be arranged casually, so there are three answers:

According to the title, there should be two rooms with 2 people, and the remaining room has 1 person, first select three people in one room and divide one, which is a53=60, and there are two people left, divided in any two rooms, which is a32=6. But there is a duplication of two rooms divided into two people, it is a22=2, so the final result is 60*6 2*2=90Is that right?

To think of it this way, at least 1 person in each room, at most 2 people, that is to say, 5 people should be divided into 1-2-2 formations, right, then there are a total of 25 divisions (4 people are divided into two groups in no order is 5 divisions, plus that one person is 5 * 5 = 25), in addition, if you divide three people into three rooms, there are a total of 6 divisions, and now it is used to divide five people who can form 25 kinds of 1-2-2 formations, so there are a total of 25 * 6 = 150 divisions in this question!

There are three, (1,2,2)(2,1,2)(2,2,1) There should be only these three!

"Count a group like this.,Then start with 2 in a group.,Count a total of 15 kinds like this.,I don't know if it's right.,It's a pity it's 0 points.,But I'm okay to graduate from junior high school.。

It's very simple, first of all, let's assume that the ABC people, AB changes the house of the CDE every week. Then it's CD, then EA, and then BC

A ratio of 221 in the end.

The speed is 5 x km/h, and the distance is ykm.

then there is y 5x-y 6x=

6y-5y=45x

y=45x, the time is 9 hours.

36 minutes = hours.

200/5x+(45x-200)/

40/x+(36x-160)/5x=

200+36x-160=42x

6x=40, so 45x=45 6*40=300

Very difficult? Frightened by the title.