The content of the two equation application problems should be detailed, and each part should be exp

1. Equivalence relationship: the speed of the vehicle is equal (the speed of the large car = the speed of the small car) and the speed of the two cars is equal after t hours, then it is obtained from the title:

30+ 20t = 90-10t

Solution t=2 (hour).

At this time, the speed of the vehicle is 30 + 20 * 2 = 70 (km h) or 90-10 * 2 = 70 (km h).

Second, the equivalent relationship: profit purchase price = profit margin. Set the price to be $ x, then it is derived from the title:

90%x-250）/250 =

The solution is x=320 (yuan).

1. If the speed of the two cars is equal after t hours, it is derived from the title:

30+20t=90-10t

Solution t=2 (hour).

At this time, the speed of the vehicle is 30 + 20 * 2 = 70 (km h) 2, and the price is set to be x yuan, then it is derived from the title:

90%x-250）/250=

The solution is x=320 (yuan).

Solution: (1) v=v (big car) + a (big car) * t = v (small car) - a (small car) * t (* represents the multiplication sign).

That is, v=30+20*t=90-10*t

Solve t=2 (hours).

So v=70 km.

2) Set the price of each piece to x

Yes (90%*x-250) 250=

The solution is x=320 (yuan).

Hope you are satisfied.

Equiquantitative relationship: speed * time = distance.

Solution: It takes x hours to travel 294 kilometers.

210/5）x=294

42x=294

42x/42=294/42

x=7A: It takes 7 hours to travel 294 km.

Work efficiency * working hours = total amount of work.

Solution: Let Chubby actually read it in x days.

12x=15*20

12x/12=300/12

x=25A: Chubby actually finished reading it in 25 days.

1. Equivalence relationship: the velocity is equal.

210/5=294/x x=7

2. Equivalence relationship: The total number of pages of the book remains unchanged.

15*20=12*x x=25

1 Time difference 5 hours does it take to travel 294 km?

The equation is (294-210) (210 5) 5 7

Set the unit price of soybeans to be x yuan kilograms, and the menu price of pineapple to be y yuan kilograms.

8x+9y=

9x+8y=

x=y=soybean unit price yuan kilogram, pineapple menu price yuan kilogram.

Or, with yuan, it is learned that a kilogram of soybeans is more than a kilogram of spinach, and the price of the pineapple menu is x, and the soybean is x+, 8 (x+

If the solution is x=, then the price of the pineapple menu is yuan, and the soybean yuan is yuan.

This question is about solving a binary equation.

Solution: According to the meaning of the question, let the unit price of soybean be X yuan per kilogram and the unit price of spinach be Y yuan per kilogram, and establish a system of equations.

8x+9y=

9x+8y=

Equations are solved using the elimination method.

Equation (1)*8=64x+72y=

Equation (2)*9=81x+72y=

Subtract the two formulas to get 17x=solution x=

Substituting x= into equation (1) or equation (2), we get y=A: The unit price of soybeans is yuan per kilogram, and the unit price of spinach is yuan per kilogram.

Set soybean x yuan kilogram and spinach y yuan kilogram.

8x+9y=

9x+8y=

The solution: x= y=

In fact, this question can be figured out without equations.

First of all, yuan, which is equivalent to 1 kilogram of soybeans minus 1 kilogram of spinach, and then use yuan, for 17 kilograms of soybeans and 17 kilograms of spinach, then 34 17 = 2 yuan, which is the money of 1 kilogram of soybeans and 1 kilogram of spinach.

Through the sum problem, the sum and difference of 1 kilogram of soybeans and spinach are now known, and it is natural to find out the money for each item.

Soybeans are (2+ yuan.

Spinach for the dollar.

1. Set up a score of X in the BAI English test.

Chinese score + mathematics DU score + English score) zhi 3 = 92 + 2 (92 2 + x) 3 = 94

184+x=282

x=982, set the width to x cm.

Length and width) dao2=86

23+x)×2=86

23+x=43

x = 20 area = 20 23 = 460 square centimeters.

3. Let this number be the answer x

4x—x=

1. Set him to score n points in the English test, and get the square according to the meaning of the question.

Du Cheng: (92 zhi2 n) 3=92+2 solution: n=98

2. Let the area of this DAO rectangle be n square centimeters, and return to the equation according to the meaning of the question: answer n 23 = 86 2 23 solution gets: 460

3. Let this number be n, and get the equation according to the meaning of the problem: solve:

1. Suppose he scored x points in the English test, 92 2 x) 3=92+2

x=982, let the area of this rectangle be x square centimeters.

x÷23=（86-2×23）÷2

x=4603, let this number be xx=

Divided into x classes 15x+10=18(x-1)+4 15x+10=18x-14 18x-15x=10+24 3x=24 x=8 Books have 15x8+10=130 Assuming x classes, you can list the equation: 15

The money of the sub racket - 34 = the money brought away.

Let the ** of each racket be $x.

3x-34=200

3x=234

x=78 yuan.

2. Money for notebook + money for ballpoint pen =

Set $x per notebook.

2x+2x=x=yuan.

Dear, ** didn't shoot well, the key numbers were covered.