Xiao Wang bought 18 boxes of milk of a certain brand with a few yuan in the supermarket. After a while, he went to the supermarket and found that this kind of milk was sold at a reduced price of 0.4 yuan per box. He bought 2 more boxes with the same money than last time. How much yuan per box before the price reduction?

Xiao Wang bought 18 boxes of milk of a certain brand with a few yuan in the supermarket. After a while, he went to the supermarket and found that this kind of milk was sold at a reduced price of 0.4 yuan per box. He bought 2 more boxes with the same money than last time. How much yuan per box before the price reduction?

Let's suppose that the milk is x yuan per box before the price is reduced. According to the meaning of the question, we get: 18x = (18 + 2) (x-0.4) the solution is: x = 4. A: the milk is 4 yuan per box before the price is reduced

It's urgent. It's due tomorrow
A two digit number is more than 3 times of a one digit number. If the two digit number is placed on the left side of a one digit number to form a three digit number, then the three digit number is 8 times of the sum of the two digit number and the one digit number?
In a 60 kilometer hike, some people walk, and the other part takes a car. The two parts set out at the same place. When the car arrives at the destination, they return to pick up the walkers. If the speed of the walkers is 5 km / h, one hour ahead of the car, the speed of the car is 60 km / h?
(solved by linear equation of one variable)

1. If one digit is x, then two digits are 3x + 2
According to the meaning of the title: (3x + 2) * 10 + x = (3x + 2 + x) * 8
Then: 30x + 20 + x = 32x + 16
X=4
The two digit number is 14 and the three digit number is 144
2. Suppose that after X hours, we meet the car that comes back to meet them
According to the distance they traveled when they met, it was a back and forth equation
60*（x-1）+5*x=60*2
Then 60x-60 + 5x = 120
65X=180
X=36/13

Complete the following problems with the help of the number axis;
1. One day, Xiao Hong asked her grandfather's age, who was a math teacher and now retired at home. He said: if I were so old, you would have 40 years to be born. If you were so old, I would be 125 years old. Ha ha! Xiao Hong wondered, how old is my grandfather?

If I am so old now, I will be 125 years old. The number of my grandfather's birthday is {x + (x + 40)} + (x + 40)

For rational numbers, a, B (B ≠ 0) define the operation "*" as follows: a * b = a × B-A △ B,
Then (- 4) * 2,

(- 4) * 2, that is, a = - 4, B = 2
that
(-4)*2=（-4）×2-（-4）/2
=-8+2
=-6
If you don't know anything, you can ask me,

How many are the five digits of 12345? What is the 29th digit

There are a (5,5) = 120 5 digits in 12345
From small to large? 29th:
Among all the 120 5 numbers, 24 begin with 1, 2, 3, 4 and 5
So the 29th one starts with two
2. The second digit begins with 1, 3, 4 and 5
So 21543 is the 30th, and the reverse is 21534, which is the 29th
If the sequence number:
21345：25
21354：26
21435：27
21453：28
21534:29, 29th

The differences and relations of matrix equivalence, matrix similarity and matrix contract

Equivalence generally means that one can be changed into another by elementary transformation. In essence, only two matrices with the same rank are needed. It is a very broad condition and not widely used. A is similar to B, because there is a non dissimilar matrix P, such that PAP ^ - 1 = B. This is the most important relationship in linear algebra or higher algebra. About half of higher algebra is

The quotient of 3-digit 6 () () divided by [] is 2-digit (), which means there are several different ways to fill in a number
The quotient of 3-digit 6 * * divided by [] is 2-digit * which means there are several different ways to fill in a number
*And * should be the same number. This is a question on my girl's test paper. I solve seven kinds of questions by myself. Do you know

The quotient of three digit 6 () () divided by [] is two digits
The biggest is 69
The minimum is 10
69-10 + 1 = 60

Mathematical exponential power operation
Why can't you always do it
I don't know how to make the fraction root or how to make it
how.

According to the operation rule of exponential power, fractional exponential power should be transformed into radical, and fractional power should be transformed into fraction

There is a column of numbers 1, 3, 4, 7, 11, 18, 29 (starting from the third number, each number is just the sum of the two adjacent numbers in front of it). The remainder of the number 2006 in this column divided by 6 is_____ .

Therefore, we can write the remainder as follows: 1,3,4,1,5,4,3,1,5

695600 the best approximation of retaining 2 significant digits is
emergency

7.0x10^5