X-65% x = 70, 49 + 40% x = 89 how to solve these two equations

X-65% x = 70, 49 + 40% x = 89 how to solve these two equations

x=200,x=100

There are 16 pieces of RMB 5 yuan and RMB 10 yuan, which are worth 115 yuan in total. How many pieces of RMB 5 yuan and RMB 10 yuan?

Let 5 yuan have X sheets, then 10 yuan have 16-x sheets
5x+10(16-x)=115
5x+160-10x=115
-5x=115-160
-5x=-45
x=9
So 5 yuan has 9. 10 yuan has 16-9 = 7

What are the rules of 1, 3, 7, 17 and 41? What's the next number

3x2+1=7
7x2+3=17
17x2+7=41
41x2+17=99

Within 100, so what is the sum of prime numbers? What is the sum of all composite numbers?
How much? Urgent

Prime: 2.3.5.7.11.13.17.19.23.29.31.37.41.43.47.53.59.61.67.71.73.79.83.89.91.97 and 1151
The sum is 3898

Y = derivative of SiN x - cos X / 2 cosx
Y = derivative of SiN x - cos X / 2 cosx

y = (1/2) • (sinx - cosx)/(cosx)
= (1/2) • (tanx - 1)
y' = (1/2)(sec²x) = 1/(2cos²x)

A and B are walking on a circular road with a circumference of 30 meters. A is 1.3 meters per second, B is 1.2 meters per second. They walk from the same place with their back at the same time. After their 10th meeting, how many meters does B have to walk to return to the starting point?

[30 △ 1.3 + 1.2] × 10 × 1.2 = (30 △ 2.5) × 10 × 1.2, = 12 × 10 × 1.2, = 144 (m). 30 × 5-144 = 150-144, = 6 (m). A: B has to walk 6 meters to get back to the starting point

Two adjacent nonzero natural numbers are coprime numbers, right?

This conclusion is undoubtedly correct when 0 is not a natural number. Now 0 is also a natural number. We only need to study whether the two adjacent natural numbers "0 and 1" are prime numbers or not. According to the definition of Coprime number in volume 10 of "mathematics of six-year primary school in nine-year compulsory education", there are only two numbers with common divisor 1, which are called coprime numbers, To sum up, the common divisor of 0 and 1 is only "1", so 0 and 1 are coprime numbers. Therefore, the conclusion that "any two adjacent natural numbers are coprime numbers" is also correct. Of course, this sentence also brings a new problem to the simplest score, and you can study it by yourself

Is zero a natural number or an integer

There is no doubt that integer must include zero. Natural number whether natural number 0 includes zero or not has been debated in the world. The British textbook stipulates that 0 belongs to natural number. Because in "number" (read "mouse tree"), 0 contains its meaning. 0 means nothing. 0 apples

1 …… First row 2 3 The second row 4 5 6 The third row is 7 8 9 10, and the fourth row is arranged according to the law shown in the figure. (n, m) represents the n-th row,
The m-th number from left to right, if (4,3) represents the real number 9, what is the real number represented by (7,2)

23

Can the product of any three continuous natural numbers be divisible by 2 and 3 at the same time?

Yes
0,1,2
1,2,3
2,3,4
.
There is obviously a multiple of 2 and a multiple of 3