Column equations, best explained, how to solve column equations?

In this kind of question, there is a relationship between the purchase price, the selling price, the cost, the profit and the profit margin.

Purchase price + management fee = cost.

Ask price - cost = profit.

Profit Cost = Profit Margin.

For this question, when cost = purchase price, there are the following calculations:

Let the 60% profit of the calculator input price = x

Let the calculator with a loss of 20% (i.e. profit -20%) purchase price = y (selling price 64 - purchase price x) purchase price x = profit margin 60% then (selling price 64 - purchase price y) purchase price y = profit margin - 20% solution x = 40 yuan; y=80 yuan.

Then the total purchase price = 40 + 80 = 120 yuan.

And the total selling price = 64 2 = 128 yuan.

Then the total selling price - the total purchase price = 128-120 = 8 yuan 0, so, in this transaction, the store is making 8 yuan.

The first cost is $x, and the second cost is $s.

x×(1+60%)=64

y×(1-20%)=64

Get x=40

y=80 40+80=120 yuan.

The store sold a total of 64 2 = 128 yuan.

then earned 128-120 = 8 yuan is not allowed to plagiarize.

The first cost is $x, and the second cost is $y.

x×(1+60%)=64

y×(1-20%)=64

Get. x=40

y=80 40+80=120 yuan.

The store sells a total of 64 2 = 128 yuan.

The profit is 128-120 = 8 yuan.

Generally speaking, the solution to the burning and concealment of the column equation is:

1. The process of solving equations is the process of separating the unknown number x from other numbers.

2. The order of solving equations is exactly the opposite of the order of operations.

3. Before solving the equation, the equation should be simplified, that is, the terms of the same class should be combined.

a) The equation in the equation is to be calculated to calculate the answer. For example:

b) Terms containing x on one side of the equation should be combined. For example: 3x+6x-15=21c) uses the multiplicative distributive property to remove the parentheses.

4. Steps to solve the equation:

a) If one side of the equation is merged, the first merge achieves the purpose of simplifying the equation.

b) Let the term with the unknown number be on one side of the equation and the number on the other side of the equation.

c) Find the value of x.

5. The method of equation testing: bring the solution of the equation into the equation and test whether the left and right sides of the equation are equal.

The general steps to solve the problem are:

Clarify the meaning of the topic, find out the known conditions and the problem sought;

Determine the equivalence relationship according to the topic, and set the unknown x;

List equations based on equiquantitative relations;

solving equations; Check, write the answer.

The column equation is to replace the unknowns in the original problem with letters, and then list the equations containing the unknowns according to the equivalence relationship in the problem. This is the first step in solving the problem; After listing the equation, according to the number and number of unknowns in the equation, find the value of the unknowns, this process is called 'solving the equation', there are many ways to solve the square scum to start the journey, you need to become "yuan" according to the number of unknowns in the equation, and the highest number of unknowns in the equation becomes "several times", respectively, with different methods to solve the value. As for the method of solving equations, it is a big, complex problem, and it is not a problem that can be solved in a few books.

But if you study for a few years or decades, you may not be able to finish it.

In parentheses, you can get it first.

x to the right, to the left. Get.

It has been said that the jujube argues that the mother is 30 years old this year, Xiao Renyan Sun Ming is 5 years old, Xiaohong is 6 years old, Xiao Ming is 20 years old after 15 years, Xiaohong is 21 years old, and she should ask her mother how old she will be in 15 years, and she should be 45 years old. Xiao Ming and Xiao Hong were 25 and 24 years old when they were born.

You don't need to train the equation, just add or subtract the years spent by the orange stove, and the mother is now 30 + 15 = 45 years old, Xiao Wu is born Xiaohong, how old is the mother, and it is also a similar simple addition and subtraction.

Mom is now 30 years old, Xiao Ming, Xiaohong was born Mom was 25 years old and 24 years old respectively.

Isn't it now that there is a period of missing years? So now 30 years old, subtracting Xiao Ming's age from his current age is the age of giving birth to Xiao Li Yuming, and subtracting Xiaohong's age is the age of giving birth to Xiaohong.

Mom is 30 years old this year, Xiaohong was born at the age of Hengyan, and Xiaoming was born at the age of (+1) years old.

When Xiao Ming was born, his mother was old.

x ten 1 = 24 + 1 = 25

Set up a total of x people, y boats, by the title:

15y ten 9 = x

18 (y a 1) = x

Solution: x=144 (person).

y=9 (bars).

There were x boats in total, and this regiment had 15x + 9 people.

15x + 9 = 18(x - 1)

15x + 9 = 18x - 18

3x = 27

Number of boats: x = 9.

Number of people: 15x + 9 = 144 people.

Solution: There are a total of x boats, which is derived from the title.

15x＋9＝18（x－1），15x＋9＝18x－18，3x＝27，x＝9。

18 (9 1) 144 (person).

There are x boats in total.

15x + 9 = 18(x - 1)

x = 9 bars.

Number of people: 15*9+9=144

Solution: Let's say the apple has been eaten for x days.

4x+12=6x-8

2x=20x=10

4x10+12=52 (pcs).

Arithmetic solution: (12+8) (6-4)=10 (days) 6x10-8=52 (pieces).

Olympiad: Profit and loss issues.

A: There are 52 of these apples.

Hope it helps!

Set a plan to eat it in x days.

4x+12=6x-8

6x-4x=12+8

2x=20x=10

4x10+12=52 (pcs).

A: There are 52 of them.

1. A total of x barrels were loaded for the unraveling.

5x+5=1428

5x=1423

The numbers are not right. 2. There are x million square meters of Tiananmen Square in the solution of Tiananmen Square.

Is it big? 2x+16=72

2x=56x=28

A: Tiananmen Square has 280,000 square meters.

3. The fastest elephant can reach x kilometers per hour.

2x+30=110

2x=80x=40

A: Elephants can reach up to 40 kilometers per hour.

Solution: The length of the Second Yangtze River Bridge in Nanjing is x kilometers.

4x+ solution: x=

Answer: The Second Bridge of the Yangtze River in Nanjing is kilometers long.

16 professors, the last sentence analyzes the number of professors with one graduate student is 8, with 8 graduate students; The total number of professors with two graduate students and three graduate students is 8, with 19 graduate students; Let the number of professors with 2 graduate students be x, the number of professors with 3 graduate students be y, and the equation 2x 3y=19 x y=8 gives x is 5 and y is 8. Therefore, the number of professors with 2 graduate students is 5.

Professor X is set up with two graduate students.

2x+3x+(16-x)*1=27

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