Ask for a primary school math problem. Thank you, heroes.

To first cut a cube as large as possible on this block, it must be as wide as 20 cm (30 cm long and 25 cm high is not enough).

The volume of the cube is 20 20 20 8000 (cubic centimeters) The volume of the cuboid is 30 25 20 15000 (cubic centimeters) Originally, the remaining material was 15000-8000 7000 (cubic centimeters), but it was an irregular shape, you can draw a picture and see, according to the practical application method. Residual length: 30-20 10 (cm) The remaining width remains the same, that is, 20 centimeters, and the residual height is also unchanged due to the removal of a protruding piece, that is, 25 centimeters, therefore, only 10 20 25 5000 (cubic centimeters) can be practically applied

And then according to the formula of making the largest cylinder in the box:

5000 157 200 3425 (cubic centimeters) Answer: The volume of this cylinder is 3425 cubic centimeters.

Truncate the largest cube, the edge length of the cube should be 20 cm. The rest of the material should be a stepped object. The largest cylinder should be cut in a cuboid 10 cm long, 20 cm wide, and 25 cm high.

The top, front, and right sides of the remaining material are 10 20 = 200 (square centimeter 25 = 250 (square centimeter 25 = 500 square centimeter). The area on the right side is the largest and should be the bottom of the cylinder. Then the height of the cylinder is 10 cm, and the radius is 20 2 = 10 cm.

Because the radius looks at the shortest side of a face, it is 20 2).

The column equation is: 10 10 cubic centimeters).

A: The volume of this cylinder is 3140 cubic centimeters.

The answer should be 625 pai cubic centimeters.

After the cube is removed, there is only one thing left that resembles a stepped shape.

The largest cylinder is supposed to be cut in a cuboid with a length of 20 cm, a width of 20 cm, and a width of 25 cm, so the volume of the cylinder is a circle with a radius of 5 cm and a height of 25 cm.

Multiply the square of the volume of 5 by 25 and the answer is 625 cubic centimeters.

Cut off a cube as large as possible, with a side length of 20 cm.

Then the diameter of the cylinder is 25-5=5 cm.

Volume = cubic centimeters.

The speed of A is 4 5 of B, then the distance of line A in the same time is the distance of line B 4 5 Line B has completed the whole journey, and A has traveled the whole journey

A rest is the whole way:

AB two places have:

2 1 5 = 10 (km).

Let the speed of B be V, and the time it takes to complete AB is t, then the speed of A is V4 5, and the distance between AB is Vt, so VT TV4 5+2

So vt 5 2

VT 10 means that the distance between ABs is 10 km.

Because the area of the colored triangle is 6 square centimeters, and the base is 2 centimeters.

So: color the triangle with a height of 2*6 2 6 cm.

So: the area of the white triangle is 1 2 * 3 * 6 9 square centimeters.

So: the area of the triangle abc the area of the colored triangle + the area of the white triangle 6 + 9 15 square centimeters.

A meadow that grows grass at a uniform rate every day can feed 24 cows for 6 days and 20 cows for 10 days, so how many days can it be eaten for 19 cows?

Answer: Suppose each cow eats 1 serving of grass per day.

24 cows grazing for 6 days: 24 6 = 144 servings.

20 cows grazing for 10 days: 20 10 = 200 servings.

Difference: 200-144 = 56 parts.

These 56 parts are the average daily grass growth of grass grown in the grass in 10-6 = 4 days: 56 4 = 14 parts.

The meadow originally had grass: 200-14 10 = 60 parts.

19 cows came to eat, and 19 servings of grass were eaten every day.

In addition to eating the 14 servings that grow each day, eat the original 19-14 = 5 servings for 19 cows: 60 5 = 12 days.

Whatever the question, you have to write "solution" s abc=2015 first

There are no test questions, how can we talk about the answers!

I can help you, talk about what the problem is.

Can I use my junior high school knowledge?

To build a section of high-speed railway, the first construction team will do it alone for 63 days, and then the second construction team will do it for 28 days, and if the two construction teams work together, it will take 48 days to complete the task. Now the first construction team will do it for 42 days, and then the second construction team will complete it, how many more days will it take to complete the task?

The first construction team did it alone for 63 days, and then the second construction team did it for 28 days, which took 91 days.

If two construction teams work together, it will take 48 days to complete the mission.

Columnar formula: 63x+28y=48x+48y

x=4/3y

Now the first construction team will do it for 42 days, and then the second construction team will complete it, 42*4 3+z=48*4 3+48

z=64+48-56=56

So the second construction team still needs 56 days to complete the mission.

Hypothesis: Now the first construction team will do it for 36 days, and then the second construction team will complete it, 36*4 3+z=48*4 3+48

z=64+48-48=64

In this case, the second construction team will need 64 days to complete the mission.

Assuming that it takes X days for A to complete alone, the efficiency of A is 1 x and the efficiency of B is (1 48 1 x). According to the inscription, the equation is:

1/x×63+（1/48－1/x）×28=1。Solve this equation to yield: x=84

So B's efficiency is: (1 48 1 x) = 1 48 1 84 = 1 112, so that after a team does it for 42 days, B will do it for more days: (1 1 84 42) 1 112 = 56

Efficiency of the 1st Construction Team: (1-1 48 28) (63-28) = 1 84 Efficiency of the 1st Construction Team: 1 48-1 84 = 1 112 (1-42 1 84) 1 112

56 days. A: It will take another 56 days.

Assuming that the total amount of tasks is 1, it will take x days for the first construction team to complete alone, and it will take y days for the second construction team to complete it alone.

Then the amount of tasks completed by the first construction team per day is 1 x, and the amount of tasks completed by the second construction team per day is 1 y

According to the title, two teams work together to complete a total of 1 48 tasks per day, i.e. 1 x+1 y=1 48 (1).

The first construction team worked for 63 days and completed 63 x, and then the second construction team worked for 28 days and completed 28 y, then 63 x+28 y = 1 (2).

From (1) and (2), we can find x=84 y=112

It is known that the first construction team worked for 42 days, and the amount of tasks completed was 42*1 84=1 2

The next 1 2 is completed by the second construction team, which takes (1 2) (1 112) = 56 days.

The cooperative work can be converted into 48 days for the first team and another 48 days for the second team, and then it is found that 15 days for the first team is equal to 20 days for the second team, that is, 3 days for the first team is equal to 4 days for the second team. Then by the first condition, a team to do it alone, 63 + 28 4 * 3, that is, 84 days. (84-42) 3*4=56 (days).

A: The second team will do it for 56 days.

Answer: The daily work progress of the first construction team is x, the daily work progress of the second construction team is y, and the second construction team needs n days to complete, 63x+28y=1

48（x+y）=1

From the above, we can solve that x,y, and that n can be found by using 42x+ny=1.

4 x = 30%.

Multiply both sides by 4 at the same time

x=x=

4 x = 30%.

Multiply the two sides of the equal sign by 4 to get x=120%=