Please help! Elementary school 5th grade math, I don t know how to calculate, thank you!!

Solution: Obviously, the bottom surface of the cuboid is square.

The edge lengths can be set to a and b respectively

The question can be listed as a=b+4

2（a²+2ab）+112=6a²

The solution is a=7 b=3

So the surface area of the cuboid is 6a -112 = 182

If the height is increased by 4 cm, the surface area will be increased by 4 sides, and if 1 side = 112 4 = 28, then the bottom edge length = 28 4 = 7

High = 7-4 = 3

So the surface area of the cuboid = 7 7 2 + 7 3 4 = 182 square centimeters.

From the inscription, we know that if the length and width are equal, if the length and width are equal, if it is set to a, the height is a-4

From the inscription 4a=112, then a=28, so the height is a-4=24, so the surface area of this cuboid with a length and width of 28 and a height of 24 can be calculated to be 4256 cubic centimeters according to the formula.

If the height is x, then the length and width are both x+4

The surface area of the cube is (x+4)*(x+4)*6, and the surface area of the original cuboid is (x+4)*(x+4)*2+ x *(x+4)*4x+4)*(x+4)*2+ x *(x+4)*4-(x+4)*(x+4)*6=112

It can be calculated that x=3

So the surface area of the cuboid is 3*7*4+7*7*2=182

1. Fill in the blanks.

1 Calculations. 2.Compute.

3.Compute.

4.Compute.

5.Compute.

6.Compute.

7.Compute.

8.Compute.

9.Calculation 75

10.Compute.

2. Answer questions.

11.Compute.

12.Compute.

963 0 1028 0

13.Compute.

14.Here are two decimals: find a+b, a-b, a b, a b

a= b= 1994 0s 1996 0s

It's too much, give you the address, you can just click on it.

Average: (1*8000+2*6000+5*4000+32*2000) (1+2+5+32)=2600

Median: 2000 (40 people in total, in descending order, the average of the salaries of the 20th and 21st people is 2000).

Mode: 2000 (the number with the most occurrences).

The 48 people in the class can be divided into four parts: those who only excel in the first attempt, those who excel only in the second attempt, those who excel in both times, and those who fail in both exams. The sum of the first three parts is 48-15 = 33 people, so the number of people who excel both times is 27 + 23-33 = 17 people.

102 kilometers is the difference of hours, and it can be concluded that the difference of 102 kilometers per hour can be obtained, that is, the average passenger car travels 12 kilometers more per hour than the truck, and the average truck travels 80-12 = 68 kilometers per hour.

Of course, you have to be able to come back when you go to a class in another place, so at first you need to drive a kilometer, and you need a total of liters of gasoline, so the boss needs to add at least 10 liters of gasoline.

Yuan is used to buy a pen, yuan, so a pen yuan.

1.If there are 5 people in a boat, there are 2 more people, if there are 6 people in a boat, there are 4 fewer people, and if there are 7 people in a boat, there are 5 fewer people.

Think of it this way:

There are 4 fewer people in a boat of 6 people, and if you remove a boat, won't there be 2 more people?

There are 5 fewer people in a boat of 7 people, and if you remove a boat, won't there be 2 more people?

Explain that this number minus 2 is the least common multiple of 5,6,7.

So, the number of students in grade 5 is the least:

2.The number of first-year students is 4 5 of the second-year, and it can be assumed that the number of first-year students is 4x, then the number of second-year students is 5x

So, the number of students in the second grade is 5x 4x 5 4 4 in the first grade, and the total number of students in these two grades is 5x+4x=9x

So, the number of first graders is: 4x 9x=4 9

Second-year student population: 5 x 9 x = 5 9

1) 48-(23+15)=10 48-(27+15)=6 48-(16+15)=17 (people).

2) Set the speed of the truck to x kilometers (80-x) by yourself.

3) ( Solve it yourself.

4) 3 times is also to solve by yourself.

Divide by the speed difference.

80-12=68 The speed of the truck is 68

Multiply and divide by liters. 8 times 3 + 5x=

x=pen.

Analysis: When the first appearance of a relative square, that is, when the height is 8cm, the left and right sides are squares. The second time, when the height is 10cm, the front and back are square.

In other words, the height before putting in the goldfish is 8, and the height after putting it in is 10, that is, the volume of the water that rises by 2cm is the volume of the goldfish.

Answer: 10 8 (10-8) = 160 cubic centimeters to teach primary school math, believe me.

When the first opposite surface is square, that is, the height of the water surface is equal to the width, then the volume of water in the container is:

10 8 8 640 (cubic centimeters).

When the opposite surface is square for the second time, that is, the height of the water surface is equal to the length, then the volume of water in the container is:

10 8 10 800 (cubic centimeters).

The volume of a goldfish is the difference between the two mentioned above:

800 640 160 (cubic centimeters).

Measuring 10 cm long and 8 cm wide from the inside, i.e. this cuboid is a cube with a length of 10 cm, a width of 8 cm, and an unknown height.

When the square appears for the first time, it is exactly 8 cm high of water, so the volume of water at this time is: 10 * 8 * 8 = 640 cubic centimeters.

Add the goldfish, the second appearance of the opposite side is a square, then the height of the water to 10 cm, then the volume of water plus goldfish is:

10*10*8=800 cubic centimeters, so the volume of the fish is 800-640=160 cubic centimeters.

Solution: Derived from the question.

10-8) x 8 x 10 = 160 (cubic centimeters).

A: ——

The proportion of drawing works is 2 15 + 1 5 = 1 3, which is one-third.

The proportion of calligraphy works is 1 3 + 1 5 = 8 15, eight-fifteenth.

The proportion of paper-cut works and painting works is 2 15 + 1 3 = 7 15, seven-fifteenth.

Two fifteenths plus three fifteenths equals five fifteenths of a painting.

Five-fifteenth plus three-fifteenth equals eight-fifteenth calligraphy.

Two fifteenths plus five fifteenths equals seven-fifteenths total.

The first answer is one-third, the second answer is eight-fifteenth, and the third answer is seven-fifteenth.

The sum of the areas of the triangle ABE and DEC is equal to half the area of the rectangle (15 12 2 = 90). The area of the triangle GBC is equal to a quarter of the area of the rectangle (15 12 4 = 45), and the sum of the area of the triangle HBE and FEC is equal to the area of the GBC minus the EFGH of the quadrilateral (45-10 = 35), so the area of the shaded part is equal to 90-35 = 55 (square centimeters).

solution, let ab be s dry rice, a, b velocity is x, y.

then s (x+y)*x=40

3s/(x+y)*x=s+35

then s=3s (x+y)*x-35

40x30-35=85

120 5 24 (cm), 24 4 6 (cm), 6 6 6 = 216 (square centimeter), 216 120 336 (square centimeter).