In a class, there are 5 boys less than 5 / 9 of the class, and 11 girls more than 3 / 7 of the class Arithmetic

In a class, there are 5 boys less than 5 / 9 of the class, and 11 girls more than 3 / 7 of the class Arithmetic

(11-5)÷（1-5/9-3/7）
=6÷（1-35/63-27/63）
=6÷1/63
=378

There are 56 students in a certain class, five out of eight of whom are boys. Three out of seven boys are three good students. How many boys in this class are three good students?
How many of the boys are good students

Male = 56 * (5 / 8) = 35
Three good students among boys = 35 * (3 / 7) = 15

How to simplify the calculation of 6A + 13a, 6x-28-2.5x + 30.58a - (5a + 8) (5x + 7) - (4x + 0.18)?
① 6A + 13a ② 6x-28-2.5x + 30.5 ③ 8A - (5a + 8) ④ (5x + 7) - (4x + 0.18) can't see clearly

6a+13a=19a
6x-28-2.5x+30.5=3.5x+2.5
8a-(5a+8)=8a-5a-8=3a-8
(5x+7)-(4x+0.18)=5x+7-4x-0.18=x+6.82

On a 130 cm square paper, draw a 240 m, 180 m wide rectangular playground plan
A.1/20 B.1/200 C.1/15 D.1/150

Consider only the length of the rectangle
The length of the rectangle is 240 meters
The side length of the square is 130 cm
130：24000≈1：185
The scale should be less than 1:185
Option B

Mathematician's story 50 words
There should be about 50 words of stories about famous mathematicians and mathematicians

One day, when Chen Jingrun was having lunch, he felt his head. Oh, his hair was too long. He should have a haircut. Otherwise, when people saw him, he thought he was an aunt. So, he put down his job and went to the barber shop

The meaning of the name of Booker Bookstore
There are Chinese everywhere in our life. If you pay attention to the shop names on the street and savor them carefully, you will find that their language is concise and rich in connotation

It is the literal translation of book

The following figure (isosceles trapezoid) is composed of three equilateral triangles. Divide them into four equal sized blocks with the same shape?
Who can help me!

This isosceles trapezoid is ABCD, e is the middle point of the bottom, Abe, AED, Dec are three regular triangles
Take be midpoint P, AE midpoint Q, de midpoint R, CE midpoint s,
Connect PQ, QR, rs
Abpq, aqrd, DRSC and psrq are four blocks of the same shape and size

What are the symmetry axes of line segments? How many are they? What are the symmetry axes of angles? What are the symmetry axes of isosceles triangles? How many are they

The axis of symmetry of a line segment is the vertical line where the middle point lies, and there is one. The axis of symmetry of an angle is the square line of the angle, and there is one. The axis of symmetry of an isosceles triangle is the line where the height of the bottom lies, and there is one

The bivariate linear equation 3x-2y equals 1 2x + 3Y equals - 7 the values of X and y

X:-11/13Y:-23/13

Given that a and B are nonzero vectors, and | B | = 2 | a |, | A-B | = root sign 3 | a |, find the cosine of the angle between a and a + B

|(a-b) (a-b) (a-b) (a-b) (a-b) (a-b) (a-b) (a-b) (a-b (a-b) (a-b (AB) = 5 (a-2-2 (AB) = 3 (a-a-2-2 (AB) = 3 (A-A, so: ab = (a-b) (a-b) (a-b) (a + b) (a + b) (a + b) (a + b) (a + b) (a + b) (a + b) (a + b) (b) (as as as this is the "a [[[[[[[124sesese124]] [[[[[[[[[[[[[[[[124124]]]]] nono124this this is a] this is a" this is a "where this is a" in this this is a "where this is a" where this is a "is a" where you is a "in this this this is the where where you you is a" in this this this is a, where you is a "(a + b) = | a | ^ 2 + AB = | a | ^ 2 + | a | ^ 2 = 2 | a | ^ 2 = | a | * | a + B | * cos