The students of four classes in grade seven of a school plant trees voluntarily on the tree planting day. Class one plants x trees, class two plants 40 trees less than twice of class one, class three plants 30 trees more than half of class two, and class four plants 30 trees more than half of class three. (1) how many trees do the four classes plant? When x = 60, which of the four classes has the most trees?

(1) ∵ x trees are planted in the first class, x-40 trees are planted in the second class, 12 (2x-40) + 30 = (x + 10) trees are planted in the third class, 12 (x + 10) + 30 = (12x + 35) trees are planted in the fourth class, and X + (2x-40) + (x + 10) + (12x + 35) = (92x + 5) trees are planted in the four classes; (2) when x = 60, 60 trees are planted in the first class, 2x-40 = 80 trees are planted in the second class, x + 10 = 70 trees are planted in the third class, and 12x + 35 = 65 trees are planted in the fourth class The second class planted the most trees

Given a & # 178; = a + 1, find the value of the algebraic formula A ^ 5-5a + 2

a^5-5a+2=a³×a²-5a+2 =a³(a+1)-5a+2 =a^4+a³-5a+2 =(a²)²+a×a²-5a+2 =(a+1)²+a(a+1)-5a+2 =a²+...

In return for Gu's "buy four and get one free" activity for mineral water. Originally, each bottle of mineral water was 2 yuan, but now the actual discount is? 2%

1 / 4 or 25%

How to do the word filling game on page 9 of new concept English 1B
ACTOSS 1 There are some green fields behind the c_ _ _ _ _ .3 London is on the R_ _ _ _ Thames.4 Are you r_ _ _ one two three,catch!5 some men +some women=some _ _ _ _ _ _ .
DOWN 1 That's the photographer's new c_ _ _ _ _ .2 Oh ,look!There's Tower B_ _ _ _ _ ,and it's open.
1_ _ _ _ _ _ +
_ + + + + + _ two
_ + _ _ _ _ _ three
_ + + + + + _
4 _ _ _ _ _ + _
_ + + + + + _
+_ _ _ _ _ _ Note: because you don't know how to use the grid form, you can use -- -- instead of the blank space and + + instead of not filling in the grid. By the way, 2 refers to the next row, and 3 refers to the five letters in the third row. If you are interested, you can draw your own square grid to challenge! I just can't think of Down's 1? Look at you!

It's a pity that I only have the youth version of new concept 1a. If there are any books, I can discuss them with you

A passenger car and a freight car leave from a and B at the same time. The passenger car runs 80 kilometers per hour, and the freight car runs 60 kilometers per hour. After five hours, the two cars run together
Q: how many kilometers are the railway plants in a and B

(80+60)×5
=400+300
=700 km

Given that x = - 2 is the solution of the equation 1-ax / 2 = x / 3 + 2A (a is a known number), find the value of A

Substituting x = - 2 into the equation, we get 1 + a = - 2 / 3 + 2a and a = - 5 / 3

The distance between a and B is 150 kilometers. A and B start from a and B respectively. It takes 10 hours for them to meet each other
The distance between a and B is 150 kilometers. A and B start from a and B respectively. It takes 10 hours for them to meet each other. It is known that a's speed is 2 / 3 of B's speed, so how many hours does it take B to walk alone? A 50 / 3 B 15 C20 D 17 please write down the specific analysis ideas,

From the question meaning: a speed + B speed = 150 / 10 = 15, a speed / b speed = 2 / 3x + y = 15x / y = 2 / 3x = 6, y = 9, it is easy to get that B speed is 9, time = 150 / 9 = 50 / 3, choose a

The solution equation: ① 5x + 2x2 + x = 3x + 1; ② X2X − 5 = 1-55 − 2x

(1) Test: substitute x = - 1 into x (x + 1) = 0, so x = - 1 is the increasing root of the original equation, so the original equation has no solution; (2) multiply both sides of the equation (2x-5), get x = 2x-5 + 5, get x = 0. Test: substitute x = 0 into (2x-5) ≠ 0, so x = 0 is the solution of the original equation

Party A and Party B move at a constant speed from west to east along the east-west highway. Party A walks 3 kilometers per hour, and Party B walks 2 kilometers more than Party A. Party A passes by place a at 10 a.m,
B passed by a at 12:00 noon on the same day. When did B meet a? How far is it from a?

Let x catch up with the equation a
3(x-10)=(3+2)×(x-12),
x=15,
3 (15-10) = 15 km away from land a

When the true fraction A / 7 is converted into a circular decimal, and the number of digits after the decimal point is 7, what is a?

Because 1 / 7 = 0.142857142857 (142857 cycle) so the number 2009 is 5, so a ≠ 5; because 2 / 7 = 0.285714285714 (285714 cycle) so the number 2009 is 1, so a ≠ 1; because 3 / 7 = 0.428571428571 (428571 cycle) so the number 2009 is 7, so a = 3