There are 10 natural numbers in a row. Starting from the third, each number is equal to the sum of the two numbers before it There are 10 natural numbers in a row. Starting from the third, each number is equal to the sum of the two numbers in front of it. The sum of these 10 numbers is 2002. What is the seventh number

one hundred and eighty-two

If the solution of the linear equation 3x - (x + k) = K + 4 is negative, then the inequality KX + K

Finishing 2x = 2K + 4
That is, x = K + 2 and X-1}

On national day, Xiao Ming bought a book for 8 yuan. On national day, all the books were on sale with a 20% discount

Original price * discount = current price
Let the original price be a
Then a * 80% = 8
A = 10 yuan

A natural number is either prime or composite

Error 1 is neither prime nor composite

What is the fourth root of 16?

The fourth root of 16 = ± 2
16=2*2*2*2=（-2）*（-2）*（-2）*（-2）

How to arrange the median if there are duplicate data in order?
When calculating the median, how to arrange it in order
13 15 12 13 14 12 15 17 19 11 13 14 11 13
To write complete Oh!

11 11 12 12 13 13 13 13 14 14 15 15 17 19
(13+13)/2=13

When Xiaohua solves the equation (2x-1) / 3 = (x + a) / 3-1 to remove the denominator, THE-1 on the right side of the equation is not multiplied by 3, but the solution of the equation is x = 2, find the value of a, and correctly solve the equation. I solve a = 4, where is x equal to 2?

Substitute x = 2 into the original equation, and - 1 on the right side of the equation is not multiplied by 3
2*2-1=2+a-1
A = 2 is substituted into the original equation
（2x-1）/3=(x+2)/3-1
2x-1=x+2-3
x=0

Application problems of linear inequalities with one variable (319:57:3)
In order to afforest a section of scenic belt along the river, the municipal company plans to buy 500 seedlings of type A and type B, 50 yuan for each seedling of type A and 80 yuan for each seedling of type B. relevant statistics show that the survival rates of type A and type B are 90% and 95% respectively. If we hope that the survival rate of these seedlings will not be lower than 92%, and the purchase price will not exceed 31100 yuan, How many purchase schemes are there? Which scheme has the lowest cost for purchasing seedlings? (solve with a system of linear inequalities of one variable)

Let X be tree A and y be tree B. the meaning of the question is: x + y = 500; X multiplied by 50 + y multiplied by 80 is less than or equal to 31100; X multiplied by 90% + y multiplied by 95% is less than or equal to 92%

A bookshelf is divided into upper, middle and lower layers, with a total of 384 books. If you take out as many books as the middle layer from the upper layer and put them in the middle layer, then take out as many books as the lower layer from the middle layer and put them in the lower layer, and finally take out as many books as the upper layer from the lower layer and put them in the upper layer. At this time, the number of books in the three layers is equal. How many books were there in the middle layer of the bookshelf?

At present, there are 384 △ 3 = 128 copies in the upper, middle and lower layers, 128 △ 2 = 64 copies in the upper layer, 128 + 64 = 192 copies in the lower layer, 128 copies in the middle layer, 192 △ 2 = 96 copies in the lower layer, 128 + 96 = 224 copies in the middle layer, and 64 copies in the upper layer when the lower layer is not given to the upper layer, so there are 224 △ 2 = 112 copies in the middle layer when the upper layer is not given to the middle layer

40% of a number is exactly equal to four fifths of 40. What's the number? The equation

Let this number be X
40%X=40×4/5
40%X=32
X=32÷40%
X=80