How much is five tons and seventy kilograms plus twelve tons and eight kilograms?

Seventeen tons, seventy-eight kilos, seventeen thousand, seventy-eight kilos and thirty-four thousand, one hundred and fifty-six kilos

12 meters () is 3 meters, 20 grams is 1 / 5 of () grams, 2 / 5 of () equals 1 / 3 of 24

12 meters (1 / 4) is 3 meters, 20 grams is 1 / 52 of (100) grams, and 2 / 5 of (20) equals 1 / 3 of (24) - hope to adopt it

Party A and Party B have several books. It is known that the number of books of Party A accounts for 40% of the total number of books of the two. When Party A gives Party B 12 books, the ratio of books of Party A and Party B is 1:3
How many books do they have?

Total 12 (40% - 1 / 4) = 80 copies
Jiayou = 80x40% = 32
B you = 80-32 = 48

On the application of a basic inequality in high school mathematics
A 40m long fence forms a rectangular garden with one side against the wall. The wall is 28m long. When you ask the length and width of the rectangle, what is the largest area of the garden? And what is the largest area?

The part of the garden against the wall is x meters long
S=x(40-x)/2
=(-x^2+40x)/2
=[-(x-20)^2+400]/2

The speed of a is 30% slower than that of B, and the distance from the center of a and B is 7.5km
a. B how much do we get together

When the two cars meet, the driving time is the same. Because a is 30% slower than B, a travels 30% less than B. because the distance from the center point is 7.5 km, a travels 7.5 * 2 = 15 km less than B. If a travels x km, B travels x + 15 km

On a problem solved by system of inequalities
A cargo ship has a deadweight of 260 tons and a capacity of 1000 m & sup3;. There are two kinds of cargo to be transported, namely, 8 M & sup3; for class a cargo and 2 M & sup3; for class B cargo. In order to make full use of the ship's load and capacity (assuming that there is no gap and the cargo is just full), how many tons should be loaded for class A and class B cargo?

Let a and B each load x, y tons x, Y > = 0
From the meaning of the title:
8x+2y

Both passenger and freight cars leave from a and B at the same time. Passenger cars travel 50 thousand miles per hour, and freight cars travel 1 / 16 of the whole journey per hour. When they meet, they meet
The ratio of the distance traveled is 5:6. How many meters is the distance between a and B? It's better to use the formula instead of the equation

960km
Trucks travel one sixteenth of an hour, so it takes a total of 16 hours for trucks to complete the journey
When they meet, the distance ratio between passenger cars and freight cars is 5:6
When the truck met, it took 6 / 11 of the whole journey * 16 = 96 / 11
The time consumption of freight cars is 96 / 11 of that of passenger cars
The bus runs 96 * 50 km, which is 5 / 11 of the whole journey
So the whole journey = (96 / 11 times 50) divided by (5 / 11) = 960km

A triangle, if one of its sides is perpendicular to the projection plane. Is it a straight line in orthographic projection?

In this way, if an edge is perpendicular to the projection plane, then the orthographic projection of that edge is a point
Because three non collinear faces define a plane, the other two sides of the triangle are in the same plane
So the line where the orthographic projections of these two sides coincide
So the projection of this triangle is a line segment

The original number ratio of team a and team B is 7:3. After some people are transferred from team a to team B, the number ratio of team a and team B is 3:2. There are 120 people in team B, but how many people are there in team B

Team a now has 180 people, a total of 300 people, team B's original 3 / 10 * 300 = 90 people

Given a natural number n, the number of all natural numbers less than N and coprime with n is represented by a (n). Why is a (n) always even when n > 2?

Let n be a prime factorization n = P1 ^ N1 * P2 ^ N2 *... * PK ^ NK, where P1, P2,..., PK are prime numbers
In the numbers 1 to P1 ^ N1, which are not coprime with P1, there are the following multiples of P1,
p1,2p1,3p1,...,p^(n1-1)*p1.
So there are P1 ^ n1-p1 ^ (n1-1) = P1 ^ (n1-1) (P1-1),
Similarly, there are P2 ^ (n2-1) (P2-1) coprime numbers with P2 from 1 to P2 ^ N2,
...
From 1 to PK ^ NK, there are PK ^ (NK-1) (Pk-1) numbers with PK coprime,
Then a (n) = P1 ^ (n1-1) (P1-1) * P2 ^ (n2-1) (P2-1)... * PK ^ (NK-1) (Pk-1),
For example:
360=2^3*3^2*5
In numbers 1 to 8, coprime with 2 has 2 ^ 2 (2-1) = 4, such as 1,3,5,7
In numbers 1 to 9, coprime with 3 has 3 ^ 1 (3-1) = 6, such as 1,2,4,5,7,8
In numbers 1 to 5, coprime 5 ^ 0 (5-1) = 4, such as 1,2,3,4
There are 4 * 6 * 2 = 48 coprime with 360
Since n > 2, then there must be a prime number greater than 2, which is odd prime number. P1-1, P2-1,..., Pk-1 must have an even number, so a (n) must be even

How much is five tons and seventy kilograms plus twelve tons and eight kilograms?