1. For a job, team a will do it alone in 8 days and team B will do it alone in 10 days. How many days will the two teams work together to complete it? 2. A project. Team a works alone for 12 hours and team B works alone for 15 hours. If the two teams work together for 2 hours and then Party B works alone, how many hours will it take to complete? 3. A manuscript can be completed in 12 hours by two typists of a and B. how many hours does it take for a typist of a to type alone and for a typist of B to type alone? 4. A local train and an express train leave from station a and station B at the same time. After meeting for 20 hours, it will take 30 hours for the local train to reach station B, and how many hours for the express train to reach station a? Please write down the process clearly

1. For a job, team a will do it alone in 8 days and team B will do it alone in 10 days. How many days will the two teams work together to complete it? 2. A project. Team a works alone for 12 hours and team B works alone for 15 hours. If the two teams work together for 2 hours and then Party B works alone, how many hours will it take to complete? 3. A manuscript can be completed in 12 hours by two typists of a and B. how many hours does it take for a typist of a to type alone and for a typist of B to type alone? 4. A local train and an express train leave from station a and station B at the same time. After meeting for 20 hours, it will take 30 hours for the local train to reach station B, and how many hours for the express train to reach station a? Please write down the process clearly

Team a does it alone for 8 days, so the efficiency is 1 / 8, team B does it alone for 10 days, so the efficiency is 1 / 10, the sum of efficiency is 9 / 40, the total workload is unit "1", the cooperation time is 1 △ 9 / 40 = 40 / 9 answer: 40 / 92. Team a does it alone for 12 hours, so the efficiency is 1 / 12, team B does it alone for 10 days, so the efficiency is 1 / 15

Two adjacent natural numbers must be coprime numbers______ (judge right or wrong)

According to the meaning of Coprime number, two numbers with only 1 common factor are called coprime numbers. Because 0 and 1 have no common factor, 0 and 1 are not coprime numbers. Therefore, two adjacent natural numbers must be coprime numbers. This statement is wrong. So the answer is wrong

Is 0 a natural number? Is it an integer?

0 is a natural number but not an integer

First row 0.1 second row 0.10.1 third row 0.10.20.1 fourth row 0.10.30.30.1 fifth row 0.10.40.60.40.1
Row 6 0.10.5 1.0 1.0 0.5 0.1
So what are row seven and row eight

0.1
0.1 0.1
0.1 0.2 0.1
0.1 0.3 0.3 0.1
0.1 0.4 0.6 0.4 0.1
0.1 0.5 1.0 1.0 0.5 0.1
0.1 0.6 1.5 2.0 1.5 0.6 0.1
0.1 0.7 2.1 3.5 3.5 2.1 0.7 0.1
As shown in the figure, the seventh row is 0.10.61.52.01.50.60.1, and the eighth row is 0.10.72.13.53.52.10.70.1

At least one of the sum, difference and product of any two natural numbers can be divisible by 3

(1) There are only three results after any natural number is divided by 3. The remainder is 0, 1 and 2 respectively. Of course, if the remainder is 0, it can be divisible
(2) Given any two natural numbers, according to the remainder divided by three, it can be divided into the following two cases:
A. At least one of the two numbers can be divisible by three, that is, the remainder is 0. In this case, the product of the two numbers must be divisible by three
B. Two numbers can't be divided by 3, and there are two cases
(a) When two numbers are divided by three, the remainder is the same, that is to say, they are both the remainder 1 or the remainder 2. In this case, if the difference between two numbers is taken, they can be divided by three
(b) When two numbers are divided by 3, the remainder is different, so it can only be one remainder 1 and the other remainder 2. In this case, taking the sum of two numbers can be divided by three
Therefore, one of the sum, difference and product of these two arbitrary numbers must be divisible by three

56°53′—28°57′=?

27°56′

English translation
Explain what the teacher wants us to do,

Write a letter about coney's action to show you how to act to achieve your goal

Find the plane equation perpendicular to the origin and 2x-y + 5Z + 3 = 0, x + 3y-z-7 = 0
The main question is why we need x multiplication. Let's talk about the idea of this problem

Firstly, the intersection line of two planes is obtained. By simultaneous equations, the form similar to X / a = Y / b = Z / C is obtained. This is the standard form of spatial straight line
The normal vector of the plane equation is (a, B, c) and passes through the origin, so the equation is ax + by + CZ = 0
Multiplication by X is only one step of simultaneous equations, which is relatively simple

A total of 200 mathematical problems in Grade Seven

(2) when x = 5, find the solution of Y. 2, 5 (9 + a) × B-5 (5 + b) × a (1) simplify the whole formula. (2) when a = 5 / 7, find the value of the formula. 3, 62g + 62 (G + B) - B (1) simplify the whole formula. (2) when g = 5 / 7, find the solution of B. 4, 3 (x + y) - 5 (4 + x) + 2Y

Fifth grade math problem: the average of the three numbers is 14.25. If one number is known to be 15.08, what is the average of the other two numbers?

The average of the three groups was 14.25
The sum of the three numbers is 14.25x3 = 42.75
The sum of the two numbers is 42.75-15.08 = 27.67
67 / 2 = 13. 835