The total cost of a and B goods is 2200 yuan. A goods are priced at 20% profit and B goods are priced at 15% profit. Later, according to the market situation, they are sold at 90% profit. The total profit is 131 yuan. What are the profits of a and B goods?

Suppose the cost of a is x yuan, then B is 2200-x yuan, then: 90% × [(1 + 20%) x + (2200-x) × (1 + 15%)] - 2200 = 131, 0.9 × [1.2x + 2200 × 1.15-1.15x] - 2200 = 131, 0.9 × [0.05x + 2530] - 2200 = 131, 0.045x + 2277-2200 = 131, 0.045x + 77 = 131, x = 1200

The total cost of a and B goods is 2200 yuan. A goods are priced at 20% profit and B goods are priced at 15% profit. Later, according to the market situation, they are sold at 90% profit. The total profit is 131 yuan. What are the profits of a and B goods?

A. B and C are the three internal angles of △ ABC, where C is 60 ° and if Sina, sinc and SINB form an arithmetic sequence and Ca · (AB-AC) = 18 (where Ca, AB and AC are vectors), the length of AB can be obtained

AB vector - AC vector = BC vector, so CA vector * BC vector = 18, and angle c = 60 °, so ac * BC = 18 / cos 60 ° = 36
And Sina * SINB = (sinc) ^ 2, so ac * BC = AB ^ 2, so AB = 6

As shown in the figure, ab = 8cm, O is any point on the line AB, C is the midpoint of Ao, D is the midpoint of ob, can you find out the length of the line CD? And explain the reason

Yes. Because co = 12 · Ao, OD = 12 · ob, CD = CO + od = 12 · Ao + 12 · ob = 12 (AO + OB) = 12 · AB = 12 · 8 = 4cm

Do mathematical problem excuse me do not have train of thought, how to do

Methods: first, look for examples, see more examples. Second, do some questions without ideas, see the answers, push back Anyway, this thing has to be practiced for a long time Of course, the foundation is necessary

2 / 4 read as "yes" and 3 / 8 read as "yes"?

The meaning is that a whole is divided into four parts and occupied two parts, and so on

The definition of 20 × 3 / 4 is to find out the number of 20 3 / 4 () √ or ×?
I would like to ask you a question: the definition of 20 × 3 / 4 is to find the number of 20 3 / 4. () fill in √ or ×, I filled in √, but the standard answer is ×. Is it because it has many definitions, and there is another way to express the number of 3 / 4 of 20, which is not limited to one answer,

Yes, your explanation is right
It can not only express the number of 20 3 / 4, but also express the number of 20 3 / 4

What does Li √ 7-3 ≤ 1 / a ≤ 1 mean? Why is it written like this?

First, G (x) = (2x & # 178; - 1) / (3-2x),
And because a = (3-2x) / (2x & # 178; - 1)
So: G (x) = 1 / A
And because
G (x) is an increasing function on [x0,1], and
g(x0)=(2x0²-1)/(3-2x0)=√7-3
g(1)=1
So √ 7-3 ≤ g (x) = 1 / a ≤ 1

In MATLAB, a = [1,2,3; 4,5,6; 7,8,9] B = a (3: - 1:1,1:3)

That is, B takes the third, second, and first row of a, and all the columns, that is, B is the matrix of a flipped up and down, which is equivalent to B = flip (a)

What is the meaning of 7 / 9 times 3 / 7?

What's the fraction (front) of the following fraction
This question is three times more than seven out of nine

The total cost of a and B goods is 2200 yuan. A goods are priced at 20% profit and B goods are priced at 15% profit. Later, according to the market situation, they are sold at 90% profit. The total profit is 131 yuan. What are the profits of a and B goods?