Some elementary to junior high school math problems have a total of 6 questions

First, consider the project as unit 1Then Xiao Li's rate is 1 10, and Xiao Wang's rate is 1 15

Set: Xiao Wang took a break for x days.

It took 8 days to complete, so Xiao Li completed 1 10*8, and Xiao Wang completed 1 15*(8-x).

1/10*8+1/15*（8-x）=1

x = 5 two, set up the original plan to plant trees x lessons.

On the first day, 3 8*x trees were planted, on the second day, (1-3 8)*2 3*x trees were planted, and on the third day, 55 trees were planted, which exceeded the original plan by 25%.

3/8*x+（1-3/8）*2/3*x+55=（1+25%）*x

x = 100 three, the pool is regarded as a unit 1, the inlet pipe has a rate of 1 8, and the outlet pipe has a rate of 1 12Because the water inflow rate is greater than the water output rate, it can be filled with water.

If the water is turned on for 2 hours, then 1 8 * 2 = 1 4 water is entered, and 3 4 water is not irrigated.

Because 1 8 water is in per hour and 1 12 water is out, it is equivalent to 1 24 water per hour.

3 4) (1 24) = 18 hours.

Fourth, set the total length to x meters.

The first time I used x 4+15, the second time I used (1-x 4-15) *2 5-4, there are 40 meters left, and what I used is the first time plus the second time, but the full length x doesn't know and can't solve it, so I can't.

Five. Have you finished your question? Isn't it a bad condition? ）

I don't know if that's the case:

The set price is x last year's ** price (80%*x) (1+20%)

This year's ** price (75%*x) (1+20%)

The ratio is 15 to 16

Six. Make a perpendicular line from the focal point of AC and the circle to AE, and set it to X, and the focal point of AC and the circle is D

The area of the semicircle is 10*10*

The area of the triangle ADE is 20*x2=10x

The area of shadow 1 is (157-10x) 2=

The area of shadow 2 is 157-10x+25=182-10x

Area of Shadow 2 + Semicircle - Area of Shadow 1 = Area of Triangle ABC.

182-10x+157-（

182+ec=

1.A project was completed in 10 days by Xiao Li alone, and 15 days by Xiao Wang. Now the two are cooperating, but because Xiao Wang rested for a few days halfway, it took 8 days to complete the task, and begged Xiao Wang to rest for a few days. [Equation].

2.Tree planting in schools. Three-eighths of the task was completed on the first day, the remaining two-thirds were completed on the second day, and 55 trees were planted on the third day, and the result was more than 25% of the original plan, so how many trees were originally planned to be planted [equation].

3.A pool has inlet and outlet pipes. The empty pool can be filled in 8 hours with a single inlet pipe, and the full pool can be discharged in 12 hours with a single outlet pipe. If I open the inlet pipe for 2 hours and then open the outlet pipe, how many hours does it take to fill the pool?

4.An electrician proposed: "There is a bundle of wires, the first time it is used a quarter and 15 meters of the total length, the second time it is used to use the remaining two-fifths of the 4 meters, and there are 40 meters left, I don't know how many meters of wire is used."

Able to answer the above questions for electricians. Please write down the calculation steps, and if not, explain why.

5.A TV set made a profit of 20% last year at 80% of the list price**. Due to the low **price this year, at 75% of the same price**, what is the ratio of this year's **price to last year's** price?

1.Set: Xiao Wang took a break for x days.

8*（1/10）+(8-x)*(1/15)=1x=52.The original plan was to plant x trees.

3x/8)+(5x/8)*(2/3)+55=x=1203.It takes a total of x hours to fill the pool.

2+x)*(1/8)-x/12=1

x=184.The total length of the wire is x meters.

x 4 + 15 + ((x-x 4-15)*2 5-4) + 40 = xx = 100, so use 60 meters.

5.Is there one less condition? If this year's profit is also 20%.

The set price is $x.

80% x 120%) (75% x 120%) = 16 15 triangular ABC-s semicircular ab

Therefore, let bc=x

20x/2-(x=

1 Set Xiao Wang to rest for x days. Because it takes 10 days for Xiao Li to do it alone, so he completes 1 10 every day, and in the same way, Xiao Wang is 1 15, but Xiao Wang took a break for x days halfway, so he completed 1 (15+x) on average every day, then the two of them completed it together every day is 1 10+1 (15+x) The question said that it was completed in 8 days, so the daily completion is 1 8, so the column equation 1 10+1 (15+x)=1 8 (solve it yourself, I believe you can solve it correctly, look at you!) )

2 Set up a total of x trees. On the first day, it was (3 8)*x, and the remaining x-(3 8)*x trees were left, so on the second day, it was [x-(3 8)*x]*(2 3).

The number of pieces added in three days is 25% more than the total number So the equation is (3 8)*x+[x-(3 8)*x]*(2 3)+55=x+25%*x

3 can be fully charged in x hours. The inlet pipe enters 1 8 per hour The outlet pipe comes out 1 12 per hour So the equation 2 * (1 8) + x * (1 8) - x * (1 12) = 1

4 Let the overall length be x meters. x-[(1 4)*x+15+(3 4)*x*(2 5)-4]=40 Finally, x-40 is used to obtain the length used, and if the x is less than 40, it cannot be.

5 Is there one less condition? If this year's profit is also 20%.

If the price is set to x yuan, then the equation can be listed (80% x 120%) (75% x 120%) = 16 15

6 Let bc be x plus the area of the white part is a semicircle, the area is 50, white plus is the trigonometric area is 10x, and the idea of the equation is add white - add white = 25, so 10x-50 = 25

Exhausted! My QQ is 524380007

A water pipe can fill the pool in 9 hours, so a water pipe can be filled with 1200 9 = 400/3 (liters) per hour

The B water pipe can fill the pool in 10 hours, so the B water pipe is filled with 1200 10 = 120 (liters) per hour

The drainage pipe can discharge x liters of water per hour, and the original water is discharged at the same time as the same amount of the old forest system, and the column is blocked.

x-400 3)*3=(x-400 3-120)*5 to get x=1300/3

Then there is a total of water per mu (1300/3 - 400/3) * 3 = 900 liters.

1.If the ratio of the radius of the bottom surface of a cone to a cylinder is 1:2, and the ratio of height is 2:3, then the ratio of their volumes is (1):18).

and b are both natural numbers not less than 1, and if a-b = 27, then the minimum value of the product of ab is (28).

and b are both two-digit integers, and a:b=5:3, then b is maximum (57).

4.There is a cup of brine, the ratio of salt to water weight is 1:4, after adding 6 grams of salt, salt accounts for 1 3 of the weight of the brine, this cup of salt water turned out to be (30) grams.

5.Cut a 2 8 8 (in centimeters) box down from the top of a cube and cut off the box.

The volume is the volume of the remaining box (1/3).

6.There were 49 students visiting the Botanical Gardens. The ticket is 10 yuan for one person, and 80 yuan for each ticket for 10 people, and they need to buy tickets at least (400) yuan.

7.The three inner angles of a triangle are not equal, the smallest of which is 45°, and this triangle must be (d).

a.Isosceles triangle bRight triangle cObtuse triangle dAcute triangle.

The first question above is wrong, hehe, I did it faster than me, but unfortunately the volume of the vertebral body was not multiplied by 1 3

According to the answer: bc + 6 = 2 5 ab have: bc = 2 5 ab -6bc + 54 = 3 5 ab have:

bc = 3 5 ab -54 so there is: 3 5 ab -54 = 2 5 ab -6, i.e.: ab = (54-6) (3 5-2 5) = 240 (km).

Because BC+6 is the 2 5 of the whole process, and BC+54 is the 3 5 of the whole processSo the complete column formula should be [(BC+54)-(BC+6)] (3 5-2 5)=240 (km), understand?

BC+54)-(BC+6)] (3 5-2 5)=240 (km), you can use this formula.

This problem can be seen intuitively through the line diagram, you can try it.

Day 1: A a---k---c---b B.

The meeting point K of A and B is 6 kilometers away from point C, and KB is 2 5 of AB

Day 2: B A --K---C --- A.

The meeting point of A and B is 54 kilometers away from point C, and kb is 3 5 of AB

a --k---k---c---b

The distance between kk is 54-6 km, and kk is 3 5-2 5 of the whole journey ab then the whole journey is: (54-6) (3 5-2 5) = 240 (km). Hope it helps!

The ratio of the number of parts produced by A and B is 3:5, A can make 18 parts per hour, and B can make 30 parts per hour;

If B takes 12 hours to complete alone, the total number is 30 12 = 360.

A total of parts = 360 3 8 = 135

The ratio of the number of parts produced by A and B is 3:5, and A can make 18 parts per hour, so B can make 30 parts per hour;

And B alone takes 12 hours to complete, so a total of 30 12 = 360 parts.

So A produces a total of 360 3 8 = 135 parts.

13512×5/(3+5)×18=135

12 5 (3+5) is the time used for work, multiplied by the 18 that A does per hour.

A total of 135 parts were produced.

At the same time, the distance traveled by the gray wolf and the pleasant goat is more than:

If the distance of the gray wolf running 3 steps is regarded as the unit "1", then the gray wolf is 1 3 (one-fifth) per step, and the pleasant goat is 1 4 per step, and their distance ratio is: (1 3 4) :(1 4 5) = 16:15

If the distance for the gray wolf to catch up with the pleasant goat is x meters, then there is:

10/x=（16-15）/16

x==160

The size of each step of the gray wolf is 4 3 times the size of the joyful yang.

And the speed of the gray wolf is only 4 5 times that of the pleasant goat.

Let the time be y, so 4 3 * 4 5y = 1 * 1 * y + 10y = 150 The distance run by the gray wolf is 4 3 * 4 5 * 150 = 160 (m).

The speed ratio of the gray wolf to the pleasant goat is 16:15

The distance difference is 10 meters, 10 ((16-15) 16) = 160 meters.

I don't know how many meters each step of Gray Taro and Pleasant Goat is?

Question 1 answer 11 (3 numbers are Question 2 answers 5 and 18 or 2 and 45 Question 3 answer 2:5 34 = 4 5:17 Question 4 (kg Yuan Question 5 1280 kg Question 6 Question 7 6 and 3/5 Question 8 Question 9 108 175 lz points should be given to me, I have done n for a long time, after all, n years have not been done, I even forgot the definition, and I also helped you check the dictionary.

1.11 (they consist of 2, 3, 6).

2.18 and 5, 9, and 10 (they are negative meaning, no one can divide the other) 3 34：17=2:1

4.(Kilograms.)

5.1280 kg.

1.The sum of three different numbers is 11 and 2These two numbers can be 2 and 45 or 5 and 18 3

Question 1:1

This is a simple question, assuming that the reciprocal of the three numbers is 1, x, -x (x is any natural number), so that the reciprocal sum can be 1

So the original number is 1,1 x,-1 x,so the sum is still 1 The second question: 1 and 90,2 and 45 (there are many others) This problem actually does not have a lot of skills at all, but because it is a mutual quality (I am a few grades higher than you, I have looked up this term for a long time, I have forgotten it for a long time), and because their least common multiple is 90, it can be imagined that the product of the two numbers is 90, so you can start from 1.

For example: 1 90 = 90, 1 and 90 are coprime, which is desirable.

2 45 = 90, 1 and 45 are coplasmic, desirable.

3 30 = 90, but 3 and 30 are not coprime and are not desirable. And so on.

There's something to do, I'll add it in two days, I'm sorry.