8 math problems, there must be an arithmetic, and it will add points

Person. [（x-3）÷3＝（x+2）÷4]

square centimeters [24 2 * 2 * 2 * 3 when the three data are the smallest surface area, so choose the length 4, width 3, height 2].

3. Put the faces of length 4 and width 3 together, and arrange them in a row with the smallest area: the length is 2*10 20 cm (4*3+4*20+3+20)*2 304

4. Personally, I think there is no solution within the scope of primary school. Bottom length * width 30, (length + width) * 2 32, I didn't find the right conditions.

3 4 8 (the company commander of the square face) is 8+3 long.

Volume: 11*8*8 704 cubic centimeters.

6. The same question: the new cuboid has 4 identical faces compared with the original, and the area of each surface is 60 4 15 square centimeters. The surface area is: 15*6 90 cm from north to south.

5*2 170 square decimeters.

8. The bottom area is a square of 100 and the side length is 10 cm. The length of the rear square is 40 cm, which is the height of the cuboid.

The surface area of the cuboid: 40 * 10 * 4 + 100 * 2 1800 square centimeters.

Question 1. If the number of environmental teams is A, and the number of trees is B, then.

3a+3=b

4a-2=b

a=5 b=18

The sum of these six integers is 365 and the sum of 5 numbers 365-65=300 Because the largest number in the six integers is 65, to make one of the numbers the smallest The other 4 numbers must be the largest, and the other 4 numbers must be 64 in turn63 .62 .

60 minimum 365-65-64-63-62-61-6 = 50

The sum of the other 5 is 300

And all of them should be less than 65

So when the other 4 are the largest.

The smallest number can reach the smallest.

i.e. 64, 63, 62, 61, 50

It is equivalent to asking that the sum of 5 numbers is 300, and the maximum number does not exceed 64 to find the smallest number.

The four largest numbers are:

Minimum = 60-1-2-3-4 = 50

The largest number is already known, so the smallest number is naturally found from the remaining 5.

The sum of 5 numbers is 300, and one of them is required to be the smallest, so you make the other four as large as possible, but not greater than 65Then start from 64 and choose down, the difference between the two is the smallest and 61, and the smallest number at this time is 300-64-63-62-61=50

7 people solution: 19 3 = 6 ......1 So it should be 6+1=7 people analysis:

Look at the representation diagram above.

It's people, it's empty seats.

Because wherever you sit, you will be next to another audience.

So there is: ".

Based on one person sitting in every three seats, we get 19 3 = 6 ......1 i.e. 7 seats, I hope it will help you, if you don't understand, you can ask me again.

7, which is the least, one person for every two empty seats, so that there will be someone on the edge of the empty seat in the middle, and there must be one seat on the two seats on each side, otherwise there will be no one on the edge of the seat.

The title means that the last row can be empty for up to 2 seats in a row.

That is, 1 person for every 3 seats 19 3 = 6 (1 remainder).

So the last row sat 6 + 1 = 7 people.

One person is adjacent to each other on the left and right, so a group of three seats, one person in the middle, 3x6 = 18, and one more person in the 19th seat, a total of 7.

6 people. First of all, out of 19 seats, one for every third seat must be occupied. 19/3=6...1 This one is the first or the last, and there can be no one. So it's 6 people.

Answer: The sum of any three bags is more than 60 pieces, and the minimum is 61 pieces, and the question does not require that the weight of each bag is not equal, so you only need to ensure that each bag of sugar is at least 20 pieces, but now you need to ensure that any three bags are more than 60 pieces, so you only need to have two bags of 21 pieces and the other two bags of 20 pieces.

20, 20, 21, 21, so the sum is at least 82 pieces.

Because any three bags are over 60, each bag is greater than or equal to 20 (and at least two bags are greater than or equal to 21), so four bags are at least 82

x1+x2+x3>60

x1+x2+x4>60

x1+x3+x4>60

x2+x3+x4>60

The four formulas add up to get:

3（x1+x2+x3+x4)>240

So x1+x2+x3+x4>80

60/3=20

Instructions are more than 20 pieces per bag.

So four bags of at least 80 pieces.

220/(1+2+3)=220/6=36……4 (divided into groups, there is one blue, two yellow, three red, and the rest, then sorted by one blue, two yellow, three red).

Blue flag: 36 * 1 + 1 = 37 (+1 because the first one that comes down is blue) Yellow flag: 36 * 2 + 2 = 74 (+2 because the second and third one that comes down more is yellow) Red flag:

36*3+1=109 (+1 because the last one is a red flag) is OK!!