There are 10 required answers, and 20 points will be deducted for one wrong answer. Xiao Ming got 40 points. How many wrong questions did Xiao Ming get? How many questions can be answered correctly? Can right and wrong be restored? Xiao Ming gets 40 points, and how many questions can Xiao Ming answer correctly? Xiao Ming should get 80 points if he answers 8 questions correctly, but Xiao Ming gets 40 points

There are 10 required answers, and 20 points will be deducted for one wrong answer. Xiao Ming got 40 points. How many wrong questions did Xiao Ming get? How many questions can be answered correctly? Can right and wrong be restored? Xiao Ming gets 40 points, and how many questions can Xiao Ming answer correctly? Xiao Ming should get 80 points if he answers 8 questions correctly, but Xiao Ming gets 40 points

If all of them are right, the score will be 10 × 10 = 100. If one wrong question is equal to 10 + 20 = 30, the number of wrong questions will be (100-40) △ 30 = 2. Therefore, Xiaoming is wrong in 2 questions and right in 8 questions. Additional analysis shows that Xiaoming is right in 8 questions, which should be 80 points. Why 40 points

Fifth grade math problem (please use words) thank you
1. If each book is priced at 12 yuan, it can make a profit of 25%. If you want to make a profit of 40%, how much should you price?
2. The fruits wholesale at 1.6 yuan per kilogram are divided into first-class and second-class products with a mass ratio of 3:5. The second-class products are sold at 1.4 yuan per kilogram. If you want to make a profit of 25%, how much yuan per kilogram should the first-class products be sold?

First question:
1. Calculate the original price of the book first: set X Yuan for each book, get: 1.25x = 12
The solution is x = 9.6 yuan
To make a profit of 40%, that is 9.6 * 1.40 = 13.44 yuan
If you want to make a profit of 25%, the average price of graded fruits is: 1.6 * 1.25 = 2 yuan
Now it is known that the price of second-class goods is 1.4 yuan per kilogram. According to the ratio of first-class goods to second-class goods of 3:5, suppose the price of first-class goods is x yuan
(5 * 1.4 + 3x) / 8 = 2
The solution of the equation is: x = 3
That is, if the first-class product is sold for 3 yuan / kg, the profit will be 25%

What's the ratio between Xiao Ming's 12 math problems and those he didn't do?

If it's a primary school problem, it's an inverse proportion
It means that more problems will be solved and less problems will be solved
But to be exact, this is a problem of linear function with negative correlation
And a certain time an addend and another addend into a functional relationship!
When the product (not 0) is fixed, one factor is inversely proportional to another factor!

Function expression is integral, fractional, quadratic radical, independent variable value range

The range of integral independent variable is all real numbers; the range of fractional independent variable is to ensure that the denominator cannot be zero; the range of quadratic radical independent variable is to ensure that the quantity in the root sign is greater than zero

The sum of number a and number B is 25.3. Expanding number B by 10 times is equal to number A. what are the two numbers?
Hurry! Hurry!
Determinant!!

Let a x, B y
X+Y=25.3
X=10Y
X=23
Y=2.3

If x = 5 is the solution of the equation AX + 5 = 10-4a, then what is a

1.8

1. There are three numbers a, B and C. A is 2 larger than B and B is 11 larger than C. The average number of these three numbers is 70. What is the number?
There are several additional questions (2, there are three numbers of a, B and C, the average number of a, B and C is 30, the average number of B and C is 36, the average number of a and C is 33, how much is the average number of a, B and C?) (3, four times of a certain number plus four, Xiao Gang's wrong calculation is to add four first, and then multiply by four, the result is three times of the true number, what is this number?)

1. Let a be x, then B be X-2 and C be X-13
So [x + (X-2) + (X-13)] / 3 = 70,
The solution is x = 75,
Therefore, the values of a, B and C are 75, 73 and 62
2. Let the numbers of a, B and C be x, y and Z respectively. From the meaning of the question, we can get: (x + y) / 2 = 30, (y + Z) / 2 = 36, (x + Z) / 2 = 33
Add the three formulas to get: (2x + 2Y + 2Z) / 2 = 99, so x + y + Z = 99, so the average of the three numbers (x + y + Z) / 3 = 33
3. Let this number be x, then according to the solution of (x + 4) * 4 = 3x, we get this number x = - 16
I hope I can help you

If the augmented matrix is as follows, how to solve the equations?
The matrix is shown in the figure

Discussion:
-K^2+K+2=(K+1)(2-K)
If 2-k = 0, the equations have no solution
If 2-k ≠ 0, K + 1 ≠ 0, the equations have unique solutions
The matrix is extended to:
1 1 -K K
0 1 -1 1
0 02-k k-1 (continue to solve)
If K + 1 = 0, the equations have infinite solutions
The matrix is extended to:
1 1 1 -1
0 0 0 0
0 (continue solving)

Party A and Party B work together to make 360 parts and complete the task in 6 days. Party A makes 35 parts a day. How many can party B do?

360/6-35
Or 360-35 * 6

1.4 * 7 + x = 12.8 18.75% x minus 4.5 * 3 = 0 3.4 + 9.8 = 1.4x = 9 18 divided by 4x minus 3 = 9 how to solve these equations
3.4 + 9.8 = 1.4x + 9 1.4 * 7 + x = 12.8 18.75% x minus 4.5 * 3 = 0
How to solve these equations

3.4 + 9.8 = 1.4x + 91.4x = 13.2-91.4x = 4.2x = 31.4 * 7 + x = 12.89.8 + x = 12.8x = 12.8-9.8x = 318.75% x-4.5 * 3 = 018.75% x = 13.5x = 0.72 the last question is division or division? If division, 4x / 18-3 = 92 / 9x = 12x = 15 If division, 18 / 4x-3 = 99 / 2x = 12x = 8 / 3