How much is the quotient of 0.4 ÷ 0.84 + 2.9 multiplied by three tenths,

How much is the quotient of 0.4 ÷ 0.84 + 2.9 multiplied by three tenths,

（ 0.4÷0.84+2.9）x3/10=1.01

Write two divisions based on 15 / 4 times 4 / 5 equals three

Causes of land desertification
I hope we can separate the natural causes from the human causes

Land desertification desert is the product of arid climate. There were deserts on the earth long before the appearance of human beings. However, there is no insurmountable boundary between the desolate desert and the plump grassland. With water, lush plants can grow on the desert and become an oasis full of vitality. If there is no water and plants in the green space, it can also

In a story book of 120 pages, Xiao Ming read one eighth of the whole book on the first day and two thirds on the second day. He read the formula and wrote the right questions
120 × 1 / 8
120 × (1-1 / 8)
120 × 1 / 8 × 2 / 3

1. How much did Xiao Ming watch on the first day?
2. After Xiao Ming read 1 / 8, how many pages are left?
3. How many pages did Xiao Ming read in two days?

Complete set u = R, a = {x | x ≤ A-1}, B = {x | x ＞ a + 2}, C = {x | x ＜ 0 or X ≥ 4} if Cu (a ∪ b) C, find the range of real number a -

A is greater than or equal to - 2 and less than 5, i.e. [- 2,5]

A passenger train and a freight train leave the two cities at the same time. It is known that the passenger train travels 55 kilometers per hour. The speed ratio of the passenger train to the freight train is 11:9. The two trains meet five hours after they leave. How many kilometers is the railway between the two cities?

55 × 9 △ 11, = 495 △ 11, = 45 (km); (55 + 45) × 5, = 100 × 5, = 500 (km); answer: the railway between the two cities is 500 km long

3N & # 178; - 4-3 (n-1) & # 178; - 4 reduction

3n²-4-3(n-1)²-4
=3(n+n-1)(n-n+1)-8
=3(2n-1)-8
=6n-11

A car from a to B, 2.4 hours, two fifths of the whole journey, at this speed, how many hours can we reach B?

2.4÷2/5×(1-2/5)
=3.6 hours

How to calculate 1 × 2 + 2 × 3 + 3 × 4 + ······ + 100 × 101

101 divided by 2 = 50 one
50 times (101 times 100 + 1 times 2) = 505100
So, 505100 plus 1 = 505101
Division doesn't play

Choose a group from the following words, imagine boldly and write a passage. A, star, small tree, house B, universe, earth, moon

In this sky with stars and moon, I sit quietly in the cool under the small tree next to the house, thinking that the earth covers a wide range, but in the vast universe, the earth is only a tiny part