1. Straighten a square wireframe with a side length of 8CM, and then bend it again to make a rectangular wireframe. The length of this rectangular frame is 4 cm longer than its width. If the width of a rectangular box is x cm, its length can be expressed as (x+4) cm. According to the equivalence relation: length times width divided by 2= perimeter, the equation can be listed as: (4 x) 2 = 8 *.

2. After a chicken farm sold 25% of the chickens, there were 2 1000 chickens left. How many chickens are there in this chicken farm? If there are X chickens in the chicken farm, please list the equations.

X*( 1-0.25)=2 1000

X=28000

The original 28 thousand.

These two reservoirs store 40 tons of water. If reservoir A is filled with 4 tons of water and reservoir B is drained with 8 tons, the water storage capacity of the two reservoirs is equal. How much water did these two reservoirs initially store?

The solution originally contained 20 tons of water each, and A was poured into B, and the total water amount remained unchanged. B discharged 8 tons of water, and the total water volume decreased by 8 tons. A -4= B +4-8, A -4= B -4, A = B, 40-8=32, 32 divided by 2 =16,65438.

4. Cast a cuboid iron block with a length of 10 cm, a width of 8 cm and a height of 5 cm into a cylinder with a diameter of 20 cm. What is the height of this cylinder (no loss is calculated). The result retains two significant figures).

4. 10xπX=400

X is approximately equal to 12.73.

5. Mathematical problem: A farm has 108 hectares of forest farm and 54 hectares of pasture. To cultivate a fruit tree, it is necessary to change part of the grassland into a forest farm, so that the grassland area only accounts for 20% of the forest farm area. How many hectares of pasture area does it need to be converted into a forest farm?

5. Solution: Establish forest farm in X area.

54-x=( 108+x)*20%

X=27 (hectare)

6.* * 1 15 Members of a school actively participated in fund-raising activities. Some members each donated 10 yuan, and the rest donated to 4 yuan.

(1) If the total donation amount is 790 yuan, how many members donated 10 yuan?

(2) Is it possible that the total donation is 785 yuan? Why?

*( 1) If x individuals donate 10 yuan, then 1 15-x individuals donate to 4 yuan.

From the meaning of the question:10x+4 (115-x) = 790.

That is 10x+460-4x=790.

Simplified: 6x=330

D: x=55

That is, 55 donations 10 yuan.

*(2) Suppose the total donation may be 785 yuan, with X people donating 10 yuan and 1 15-x people donating to 4 yuan.

Meaning: You have10x+4 (115-x) = 785.

Reduced to 6x = 325

X = 54. 1666667。

Because people can only be integers, so the assumption is not true, that is, the total donation can not be 785 yuan.