The simple problem of the first year of junior high school is to solve the second problem with a one

1.If x kg of wheat is required, then x*( x=5000

2.Let the walking time be t, then t(45+36)=108, t=4 3, 4 3 hours is one hour and twenty minutes, and the meeting time is 17:20 at 16:00.

1.In order to obtain 4250 kg of flour, at least 4250 (1-15%) = 5000 hours) is needed

1.Suppose xkg of wheat is required, x(1-15%)=4250, x=5000

2.It takes t hours, 45t + 36t = 108, t = 4 3 hours = 80 minutes.

So the time of the encounter is 17:20.

Solution: (1-15%)=5000 (kg).

45 + 36) = 4 3 hours = 1 hour 20 minutes.

The time when the two cars meet is 17:20.

Solution: Suppose at least x kg of wheat is required, according to the question.

x（1-15%）=4250

x=5000

Solution: Set the two cars to meet after x hours. According to the title.

45+36）x=108

x=4/3

1 (got; 5000

2 (45+36)x=108: x=4 3;So the time for the two cars to meet is 17:20.

Start the timer from the start of the team:

The time when the team walked out of the school gate 1000m was: 1000 4000 = hours, and then the sports committee ran back to the school and took 1000 5000 = hours for the sports committee to find film (actually didn't use a digital camera, despise one) and took an hour (6 minutes).

So far, the large army has been walking for hours, while the sports council is at the school, that is, there is a distance of 4000 meters between the sports council and the large force.

The sports commissioner can catch up with 5000-4000 = 1000 meters in an hour, and the distance of 2200 meters has to chase an hour (he is tired to death).

So by the time the sports commissioner caught up with the big group, it was already an hour. At this time, the large army left the school with meters. And the large army is 1,000 meters away from the finish line, so the distance from the school to the finish line is 12,000 meters.

How to solve the equation.

The distance from the school to the destination is x meters.

x-1000) 4000 = 1000 4000 + 1000 5000 + solution x=12000

Suppose the total distance is x

A total of (X-1) km has been traveled by the retired army, and (X-1+1) has been performed by the Sports Commissioner, which is xkm. The time is the same.

So the equation is obtained:

x-1) 4=x 5+6 60 (the time of the film) is solved x=7km

1 5+1 10+(x-1) 5=(x-1) 4 The distance from the school to the destination is 7 km.

1.Set volleyball xThen (2x-3):

x=3:2 gives x=6Platoon = 6 Baskets = 2x-3 = 9.

2.Set the uncle is now age x, Xiaoqiang ythen x=2y-4 (x-y)+x=40

Uncle De x = 28 years old, Xiao Qiang y = 16 years old. 3.Set x box body and Y box bottom.

Then x+y=36 25x 40y=1 2 get the box body x=16Bottom of the box y = let 30% be x and 75% be y. then 30%x+75%y=50%*18 x+y=18

then we get x=10kg, y=8kg 5.Set the unit price of toothbrush x

Toothpaste is yThen according to the known conditions, the equation is 39x+21y=396 and both sides of the whole formula are divided by three at the same time, and the equation becomes 13x+7y=132Then multiply both sides of the equation by four at the same time, and the equation becomes 52x+28y=528

So the account of 52x+28y=518 is wrong. Thanks for the reference! Hope it helps!

1. Set the number of basketballs to x volleyball book y

2y-3=x,3y=2x

Substituting y=6,x=9

2. Set Xiaoqiang's age to be y, and Uncle X's is Y

x-4=y-x,y-x=40-y

Solution: If the engineering quantity is x, then A does x 10 per day, B does x 12 per day, and C does x 15 per day

Then: the remaining amount after 3 days of B C is: x-3*(x 12+x 15) =x-(x 4+x 5)=11x 20

The number of days required for teams A and B to do this workload is: 11x 20 (x 10+x 15)=11 20*6=days. So the final completion time for each team is: 3+, less than 7You should be able to complete the plan on time.

The equation for the column of the unary equation is to find the equation: the engineering quantity is regarded as 1, and it takes x days to complete the equation A and B. Then the column formula is:

x（1/10+1/15) = 1- 3*(1/12+1/15)

x/6= 11/20

x= 66/20=

If you know the number of days of A and B, you will know whether you can complete the amount of homework in seven days.

Solution: Let the remaining working days of A and C be x

1/12+1/15)×3+（1/10+1/15）x=1x=87/10

A: It cannot be completed within 7 days.

The combined age of the two brothers this year is 55 years old, there was a year when the elder brother was the same age as the younger brother this year, and at that time the elder brother was exactly twice the age of the younger brother, how old is the elder brother this year?

Let the cooperation of A and C be completed in x days, 1 12 + 1 15) * 3 + (1 10 + 1 15) * x = 1 to solve x = four, otherwise it will not work.

The first 72 yuan shows that the price of his book is less than 200.

So the first time I sold a book, the price was 80 yuan, and it was 8 yuan cheaper The set price was x, and the equation was; x=80

The second time he bought a book, he was given a 20% discount, so the part he bought more than 200 yuan this time was 9% off 200 yuan according to the regulations.

The remaining *** grid is 34-20-8=6 yuan.

The 8 yuan is discounted on the part of the price that exceeds 200; That is, the list price is minus 200 times, and the second time you buy the book** is y

The equation is (y-200); The solution is y=230, so he actually spent 230-34+8=204 for the second time to buy the book, and it can also be listed in an equation, let the second price be x72, and solve 8+20+x=230 yuan, and the second time he spent money, it was 230-34+8=204

Solution: 72

Let the price of the second purchase be $x

x-200) = x-(34-8), and the actual payment of x=230 is 230-26=204 yuan

Answer: Solution: I paid 72 yuan for the first time to buy a book, and I enjoyed a 10% discount, and the actual price was 72 yuan, saving 8 yuan

According to the title, the second time I saved 26 yuan

Suppose the price of the second purchase is $x (x-200), and the solution is x=230

Therefore, the actual payment for the second purchase is 230-26=204 yuan

Analysis: When cooperating for 2 hours: A completes 2 12 of the project, B completes 2 24 of the project, and a total of 1 4 of the project is completed.

The remaining 3 4 A completes: (3 4) (1 12) = 9 Total: 2 + 9 = 11

Equation: If it takes a total of x hours, then A works alone for x-2 hours 2*(1 12+1 24)+(x-2) 12=1( x-2) 12=3 4

x-2=9x=11

However, this question is a bit brain-dead, and the actual result cannot be calculated. Because the cooperation between A and B will inevitably lead to efficiency gains (in general), the time must be less than 11 hours.

The price is 900 yuan per piece.

A certain store** a certain commodity, several boxes of table tennis balls (not less than 5 boxes) ask (1), 4; When buying how many boxes of table tennis balls, the two preferential methods pay the same: 30*5+5(x 5) 5x+125

The money you need to buy at store B is the same for both preferential payment methods.

Observe the payment situation of store A and store B, and buy it at store B.

x<20, which store are you going to go to to buy it? Why? (Please use a one-dimensional equation to solve).

Solution: If you buy a table tennis ball x box, the money you need to buy it in store A is, go to store A, 5x+125=4?(2) When buying 15 boxes, it is suitable to buy at store A.

So. 5x+135

x=20 means when you buy 20 boxes of table tennis balls, go to store B: 30*5*, 30 boxes of table tennis balls. 5x+135 5x+125, when you buy 30 boxes, please do this, and let the profit of 40 yuan sell, you can still make a profit of 10%, ask for the purchase price of the product.

Set the purchase price to x900*0, when buying 15 boxes. 5x+135

Ream: 30*5+5(x 5) 30*5*0This class requires 5 pairs of rackets. In the price reduction competition, the item is sold at nine percent.

Fold ** a class will buy some table tennis and table tennis rackets, now understand the situation as follows: A, B two stores ** two kinds of table tennis rackets of the same brand, table tennis rackets are priced at 30 yuan per pair, table tennis balls are priced at 5 yuan per box, after negotiations, store A gives a box of table tennis balls for each pair of rackets, and store B is all discounted by 9% off the price, obviously when x>20

Solution: It takes a total of x hours.

By the inscription, A works alone for x-2 hours.

The columnable equations are as follows:

2*(1/12+1/24)+(x-2)/12=1(x-2)/12=3/4

x-2=9x=11

A: It takes 11 hours in total.

If the total amount of the project is 1, A completes 1 12 per unit time, B is 1 24, then it is determined by the title, and the rest is completed by A, which takes x hours.

2*(1 12 +1 24)+x*1 12=1 The solution is x=9, so it takes 9+2=11 hours in total.

Let the answer be x

A does 1 12 per hour, B is 1 24, 1 12 + 1 24) * 2 + 1 12 * x 1 x 8

The answer is 8 hours.

Looks like I've done it before... But n a long time ago... Two hours later, A made 1 6 and B made 1 12

So I did a total of 1 4, and 3 4Divide by 1 12Got 9 . . .

That is, 1 12*2+1 24*2+1 12*x=1

x=9, so a total of 11

。。Suddenly I found that 3 4 divided by 1 12 couldn't be calculated.,It took the computer to come out.。。。 Sweat...

9 hours takes x hours, A does 1 12 per hour, B does 1 24 per hour, then there is an equation.

1/12+1/24）*2+1/12x=1

Solution x=9

Let A complete the amount of A per hour and B complete the amount of B per hour, for a total of C, and A will take x hours.

By the title, get:

12a=c24b=c

solution, b=1 2a.....1）

Then by the question, get:

2（a+b）+ax=c….（2）

Substituting (1) into (2) gets:

x=9x+2=9+2=11

It takes a total of 11 hours.

It will take x hours to complete.

The parenthesis is one-twelfth plus one-twenty-fourth, and the parentheses are multiplied by two plus one-twelfth x equals one solution x equals nine.

Two plus nine equals eleven.

So it takes a total of 11 hours to complete.

If it takes a total of x hours, then A works alone for x - 2 hours.

2*(1/12+1/24)+(x-2)/12=1(x-2)/12=3/4

x-2=9x=11

It takes 11 hours in total.

It will take x hours to set. If the total task is 1, then A's rate is 1 12;B is 1 24, 1 = 2 * 1 12 + 2 * 1 24 + x * 1 12

Solution x=9

1.Let B complete the required time x alone, and obtain: (1 30 + 1 x) * 24 = 1 to calculate x = 120

2.After A completes 10 hours alone, let the time required for A and B cooperate y, then (1 30 + 1 120) * y = 1-10 30 to get y=16

3.If B has to do it alone for 5 hours and then cooperates for z hours, then (1 30 + 1 120) * z = 1 - 10 30 - 5 120 gives z = 15

Represents the multiplication sign.

If the engineering quantity is 1, then the efficiency of A is 1 12, and B is 1 24, 1 12 + 1 24) x2 + x 12 = 1x = 9

A does 1 12 per hour, B 1 24, it takes x hours, there is.

1/12+1/24)*2+x*1/12=1

Get x=9

Lazy little pot friends.

1. It took x minutes.

Then the equation is: 80 (5+x)=180 x is solved x=42, and it is far away from school y.

Then 180 4+y=1000 to solve y=280 The key is to understand and apply to other problems, little pot friend.

1 Let Daddy take x minutes to get 80 (5+x) = 180x solution to get x=4

2 1000-180x4=280 meters.