For a four digit number, the number on the hundred digit is twice that on the individual digit, the number on the thousand digit is three times that on the individual digit, and the number on the ten digit is one less than that on the hundred digit

For a four digit number, the number on the hundred digit is twice that on the individual digit, the number on the thousand digit is three times that on the individual digit, and the number on the ten digit is one less than that on the hundred digit

The biggest is the biggest in a thousand
It's a multiple of three, nine, six, three
The maximum number of a thousand is nine, so the number of a thousand is three, the number of a hundred is six, and the number of ten is five
So the four digits are 9653

For a three digit number, the number on the ten digit is 3 / 4 of the number on the one digit, and the sum of the number on the hundred digit and the number on the ten digit is 1 more than the number on the one digit
The new number is 495 larger than the original number. Find the three numbers

These three numbers ABC, then
B=3/4C
A+B-1=C
100C + 10B + a - (100a + 10B + C) = 495, i.e. 99c-99a = 495
The solution is a = 3
B=6
C=8
These three numbers are 368

A three digit hundred digit number is a. if the number on the ten digit number is one more than the number on the hundred digit number and the number on the ten digit number is one more than the number on the ten digit number, then the three digit number is a

The three digits are: 100A + 10 (a + 1) + (a + 2) = 111a + 12

(0.1x-0.2) / 0.01-6.5 = (0.02-2x) / 0.02-7.5

10x-20/1-6.5=2-200x/2-7.5
2（10x-20）-13=（2-200x）-15
20x-40-13=2-200x-15
20x+200x=2-15+40+13
220x=40
x=2/11
The process is too complicated. I didn't verify it. I don't know if it's right. If it's wrong, please tell me again

To solve the equation 0.5 / 0.2x + 1 = 0.2 / 0.1x-0.1 + 1, you can first convert the decimal in the denominator into an integer, and get____ And then go to the denominator, that is, multiply both sides of the equation
___ The equation is obtained____

To solve the equation 0.5/0.2x + 1 = 0.2/0.1x-0.1 + 1, you can first change the decimal in the denominator into an integer, and get: 5 / 2x + 1 = 2x-0.1 + 1. Then you can get the equation: 5x + 2 = 4x-0.2 + 2, x = - 0.2

The denominator in the equation x + 10.4 − 0.2x − 10.7 = 1 is changed into an integer, and the result should be ()
A. 10x+14−2x−17＝1B. 10x+14−2x−17＝10C. 10x+104−2x−107＝1D. 10x+104−2x−107＝10

According to the nature of the fraction, the numerator and denominator of each fraction are multiplied by 10 to get: 10x + 104 − 2x − 107 = 1

1. The denominator of the equation 0.03 2 / 3 (x + 1) = 0.06 is reduced to an integer, and the obtained equation is () 2. The solution of the equation 2x + 1 / 3 = 0 is () directly written empty

1. The denominator of equation 0.032 (x + 1) = 0.06, i.e. 2 (x + 1) / 0.03 = 0.06, is reduced to an integer, and the equation obtained is: 10000 (x + 1) / 3 = 3, i.e. 10000 (x + 1) = 9. A: the denominator of equation 0.032 (x + 1) = 0.06 is reduced to an integer, and the equation obtained is (10000 (x + 1) = 9)

Xiao Ming found that the coefficients of the first term of these equations are even when he solved the equations ① x ^ 2-2x-2 = 0, ② 2x ^ 2-4x + 1 = 0, 3. X ^ 2 + 6x + 3 = 0. He speculated that the quadratic equation with one variable should have its own root formula. Please help Xiao Ming to complete this idea (let the equation AX ^ 2 + BX + C = 0, and B = 2n.)

Let the quadratic equation be ax ^ 2 + 2nx + C = 0,
Then x = [- 2n ± √ (4N ^ 2-4ac)] / 2 = - n ± √ (n ^ 2-ac)

Solving equation 25.5-2 (2.5-2x) = 50.5
Specifically,

25.5-2(2.5-2x)=50.5 25.5-5-4x=50.5 -5-4x=50.5-25.5 -4x=25+5 x=30÷(-4) x=-7.5

How to solve the equation 25 / 4 △ 1 / 2x = 5 / 3?
Practical questions
1. The number of literature and art books in school library is 1 / 6 less than that of science and technology books
① There are 246 science and technology books, and how many literature and art books are there? 2. There are 205 literature and art books, and how many science and technology books are there?
2. The hotel bought 7 / 8 tons of flour. It used 3 / 14 of this batch of flour on the first day and 3 / 16 on the second day. How many tons of flour do you use?
3. The school bought a laptop with a price of 6000 yuan. After negotiation with the store, the school gave 10% discount after 20% discount. How much did it cost to buy this laptop?
4. There is a batch of cement on the construction site, which is 1 / 4 of the total in the morning and 2 / 5 in the afternoon. In the afternoon, 12 tons more than in the morning. How many tons of this batch of cement are there?
Review the test paper! 30 points!

（1）246x1/6=205 （2）205x5/6=2462.7/8*3/14+3/16=3/83.6000*0.8*0.9=43204.12/（2/5-1/4）=80