It costs 84.36 yuan to buy 30 story books and 24 science and technology books. Each story book costs 0.4 yuan more than science and technology books. How much is the price of each story book and science and technology book

Suppose the price of science and technology book is x yuan, and that of story book is (x + 0.4)
Then 24x + 30 (x + 0.4) = 84.36
The solution is x = 1.34
So (x + 0.4) = 1.74
A: each story book costs 1.74 yuan
Each science book is 1.34 yuan

Xiao Ming read a story book and Xiao Fang read a science and technology book. The number of pages in the story book is 75% of that in the science and technology book. Xiao Ming read 15 pages a day and Xiao Fang read 18 pages a day. They started reading at the same time. When Xiao Ming finished reading the story book, Xiao Fang had 24 pages left. How many pages are there in each of the two books?

Suppose that the science and technology book has x pages, then the story book has 75% x pages, and the following equation can be obtained: & nbsp; & nbsp; & nbsp; & nbsp; X − 2418 = 75% x15, & nbsp; (x-24) × 5 = 6 × 75% x, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 5x-120 = 4.5X, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 0.5 = 120, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 240.240 × 75% = 180 (pages) a: there are 280 pages of story books and 240 Pages of science and technology books

Xiao Ming read a story book and Xiao Fang read a science and technology book. The number of pages in the story book is 75% of that in the science and technology book. Xiao Ming read 15 pages a day and Xiao Fang read 18 pages a day. They started reading at the same time. When Xiao Ming finished reading the story book, Xiao Fang had 24 pages left. How many pages are there in each of the two books?

Suppose that the science book has x pages, then the story book has 75% x pages, and the equation is: & nbsp; & nbsp; & nbsp; & nbsp; X − 2418 = 75% x15, & nbsp; (x-24) × 5 = 6 × 75% x, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 5x-120 = 4.5X, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp

Xiao Ming read a book and Xiao Fang read a science and technology book. The number of pages in the story book is 75% of that in the science and technology book. Xiao Ming read 15 pages a day and Xiao Fang read 18 pages a day. They started to read at the same time. When Xiao Ming finished reading the story book, Xiao Fang still had 12 pages to read. How many pages are there in each of these two books?

Science: 120
Story: 90
Equation: suppose science book x page: 0.75x * 18 / 15 + 12 = x
Solution, x = 120

The radius of the sector AOB is 3cm, and the degree of the central angle is 120 degrees. If the sector is enclosed into a cone, what is the side area of the cone

120°÷360°=1/3
1 / 3 × π × 3 & # 178; = 3 π CM & # 178;

As shown in the figure, in the triangle ABC, AB equals AC and BD is the height on the side of AC. what is the quantitative relationship between CBD and a

Angle CBD + angle c = 90 °,
AB = AC, so angle c = angle B, angle c = 1 / 2 (180 ° - angle a),
Substituting angle CBD + 1 / 2 (180 ° - angle a) = 90 °,
So angle a = 2 angle CBD

How to solve a problem of absolute value inequality with parameters?
|A-2x | > X-1, is constant for X ∈ [0,2], and the value range of a is obtained. [the answer is: a ∈ (negative infinity, 2) ∪ (5, positive infinity)]
How to solve this problem? Why can't we get rid of the absolute value directly with the formula? How to solve the absolute value inequality with parameters is the fastest and best way? Please be more detailed. I'm a junior in high school. I'm very urgent! At the same time, thank you very much!

Analysis: because the difficulty of solving this problem is that we don't know the number on the right side of the inequality sign (that is, it's hard to judge whether it's positive or negative), so it's difficult to deal with it. Therefore, we should divide it into two kinds of hypothesis, and then discuss it, so as to simplify it
(1) when X-1 ≥ 0 (that is, a non negative number), X ≥ 1, then (solve the general inequality): (2) if X-1 ≥ 0 (that is, a non negative number), X ≥ 1, then (solve the general inequality)
① a-2x>x-1
a>3x-1
∵ 1≤x≤2
∴ 2≤3x-1≤5
Because a is greater than 3x-1, it is greater than the maximum value of 3x-1,
That is, a > 5
② Because X-1 is nonnegative, then:
a-2x

The circumference of a semicircle is 10.28cm. What's its radius?

Let the radius be r
2r+3.14*r=10.28
5.14r=10.28
r=10.28\5.14
r=2
A: its radius is 2 cm

Let's talk about the reason. Given the line segments a, B, C and D (B ≠ d), if AB = CD, does a − CB − d = a + CB + d hold? Why?

If AB = CD, then a − CB − d = a + CB + D holds. The reason is as follows: let AB = CD = k, then AB = − C − d = K. according to the proportional property, we can get a − CB − d = k, a + CB + D = K, a − CB − d = a + CB + D. so when AB = CD, a − CB − d = a + CB + D

How to calculate the multiplication of polynomials with the same coefficients, such as: (x + 3) (x + 3) (x-3) (x + 3)
Which has changed its number

If you have (x + 3), put it forward
Original formula = (x + 3) (x + 3) · (x + 3) (x-3)
=(X+3)[(X+3)(X-3)]
=(X+3)(X²-9)
=X Cubic + 3x & # 178; - 9x-27

It costs 84.36 yuan to buy 30 story books and 24 science and technology books. Each story book costs 0.4 yuan more than science and technology books. How much is the price of each story book and science and technology book