Solution:
l+300=30v
300-l= 10v
v= 15m/s
L =150m
Answer: vehicle length150m, speed15m/s. ..
2. A class of students went to Beishan for an outing, 18km. There is only one car, so it needs to be divided into two groups. Group A takes the bus first, and Group B walks. The bus goes to Group A, Group A gets off and walks, and the bus goes back to Group B. Finally, the two groups arrive at Beishan at the same time. Given the car speed of 60km/h and the walking speed of 4 km/h, find the distance from point A to Beishan.
Let the speed of a be x and the speed of b be y.
80x+80y=400
80y-80x=400
So x=0 y=5 (the time of this question is 80 seconds, which is not true)
3. Let the distance from point A to Beishan be X, and when the car returns to group B, the distance from point B to the starting point is Y..
Then [x-4 * (18-x-y)/60]/4 = (18-y)/60.
y/4 =( 18-x)/60+( 18-x-y)/60
So x=2 y=2.
Point A is 2 kilometers away from Beishan.
3. Peony Cup football match 1 1 round (that is, each team needs to play 1 1 game). If you win a game, you will get 3 points, if you draw a game, you will get 1 point, and if you lose a game, you will get 0 point. The team of Guoxing Sangao Club won four times as much as it lost, and the result was * * * 25 points. The team won the trophy.
Let x win and y lose, then 1 1-x-y will be even.
x=4y
3x+ 1 1-x-y=25
x=8
y=2
Eight wins and two losses 1 draw.
In extracurricular activities, some students take part in group activities. Originally, there were 8 people in each group, and then they were regrouped, and each group had 12 people, which decreased by 2 groups. How many students are there?
Suppose there is an X organization. So the number of people is 8x.
(x-2) 12=8x
x=6
* * * There are 48 people.
5. There is a high-speed wind belt above the surface 10 km. Suppose there are two planes flying at the same speed in this wind belt, and one of them flies from A to B, the distance is 4000 meters, which takes 6.5 hours; At the same time, another plane flew from B to A in only 5.2 hours. What is the average speed of the plane and the wind?
Let the average speed of the aircraft be xkm/h and the wind speed be ykm/h.
From the meaning of the question, we can see that there is headwind from A to B and tailwind from B to A, and the countable equation is:
x+y=4/5.2
x-y=4/6.5
Solution: x = 9/ 13, y =113.
6. A team travels at a speed of 5 kilometers per hour. Twenty minutes later, a correspondent caught up with the team at a speed of 15 km/h. How many hours will it take him to catch up with the team?
5*( 1/3)+5*X= 15*X
x= 1/6
6. A harvester harvests 12 hectares of wheat every day. Cutting 2/3 of the wheat field improved the efficiency by 5/4 times, so it was completed 1 day ahead of schedule. How many hectares of wheat fields are there?
Assuming that the wheat field is x hectares, because two thirds of it has been cut, there is still 1/3 left, and the equation is obtained:
( 1/3)x/ 12 =( 1/3)x/[ 12 *(5/4)]+ 1
Simplify:
(5/3)x=(4/3)x+60
( 1/3)x=60
x= 180
So the wheat field has 180 hectares.
7. Party A and Party B invest in the company according to the ratio of 2: 5, and agree to share the profits according to the investment ratio. If the profit in the first year is 14000 yuan, how much should Party A and Party B share respectively? Solutions of equations
Solution: let every minute be divided into X.
2X+5X= 14000
7X= 14000
X=2000
2X=4000
5X= 1000
So A gets 4000 yuan and B gets 10000 yuan.
8. According to the regulations of civil aviation, an ordinary class passenger can carry up to 20 kilograms of luggage for free, and the excess can be purchased at the ticket price of 15% with the baggage ticket. A passenger carries 35 kilograms of luggage, pays the air ticket and baggage ticket 1323 yuan, and asks for the passenger's air ticket fee.
Please do equations to solve application problems.
Set the fare to x yuan.
x+(35-20)* 1.5% x = 1323 x = 1080
(It should be 1.5% per kilogram, not 15%) It is impossible to charge that high. If it is so high, the calculation result is not an integer, which is not in line with the actual fare of the air ticket. If it is charged according to 15%, the answer is 407; if it is charged according to 1.5%, the answer is 6544.
9. When a store sells two goods with the same price, one of them gains 25% and the other loses 25%. Is it a profit or a loss to sell these two goods?
Solution: Suppose the prices of these two commodities are both X yuan.
Because the purchase price is x/(1+25%)+x/(1-25%) = 4/5x+4/3x = 32/15x.
The price is, x+x=2x.
32/ 15x & gt； 2x instant purchase price > price
So lose money
10. It takes 30 seconds for the train to completely pass the 300-meter-long iron bridge, and it takes 10 seconds to completely stay on the bridge. The length and speed of the train.
Solution:
l+300=30v
300-l= 10v
v= 15m/s
L =150m
Answer: vehicle length150m, speed15m/s. ..
Responder: Shan Lan-Trainee Magician Level 2 3-9 2 1:35.
Evaluation is closed.
Respondent: President of Yu No.1 Primary School1Grade 7-29 15:00.
A workshop can produce 120 type A parts, 100 type B parts or 200 type C parts every day. Three A-type parts, two B-type parts and 65,438+0 C-type parts can be made into a set. Now it is required to produce the most complete set of products within 30 days. How many days does it take to produce three parts, A, B and C?
1. A group plans to make a batch of "Chinese knots". If everyone does five, it will be nine more than planned. If everyone does four, it will be less than planned 15. How many team members are there? How many Chinese knots do they plan to make?
There are x members in the team.
5x=4x+ 15+9
5x-4x= 15+9
2.
A middle school organizes a spring outing for junior one students. It was originally planned to rent a number of 45-seat buses, but 15 people had no seats. If you rent the same number of 60-seat buses and have one more, the rest will be just full. We want to ask
(1) What is the number of students in Grade One? How many 45-seat buses were originally planned to be rented?
Solution: Rent 45-seat bus X and 60-seat bus (x- 1).
45x+ 15=60(x- 1)
Solution: x=5 45x+ 15=240 (person)
The number of students in Grade One is 240.
It is planned to rent five 45-seat buses.
3. Input a batch of accounting statements into the computer. It takes 20 hours for Party A to do it alone, and it takes 12h for Party B to do it alone. Now Party A works alone for 4 hours, and the rest is done by both parties. How long will Party A and Party B cooperate?
Solutions; Set to XH
1/5+ 1/20X+ 1/ 12X = 1
8/60X=4/5
X=6
The cooperation time of A and B is 6H.
4. The sum of the numbers A, B and C is 53, so the ratio of A to B is 4: 3, C is 2 less than B, B is () and C is ().
Let a be 4X. Then b is 3X. C is 3X-2.
4X+3X+3X-2=53
10X=53+2
10X=55
X=5.5
3X= 16.5
3X-2= 16.5-2= 14.5
B is 16.5 and c is 14.5.
The length of thick candle is the same as that of thin candle. Thick candles can burn for 5 hours, and thin candles can burn for 4 hours. After the power failure, two candles are lit at the same time, and they are extinguished at the same time after the call. It turns out that the length of a thick candle is four times that of a thin candle. How long will it take for the power outage?
Set the power outage for x hours. The thick candle burns 1/5 per hour, and the thin candle burns 1/4 per hour.
1- 1/5X = 4( 1- 1/4)
1- 1/5X=4-X
- 1/5+X=4- 1
4/5X=3
X= 15/4
6. For a three-digit number, the number of the hundredth digit is greater than the number of the tenth digit 1, and the number of the tenth digit is three times smaller than 2. If the order of three digits is reversed, the sum of the obtained three digits and the original three digits is 1 17 1, so find these three digits.
Let ten digits be x.
Then100× (x+1)+10x+3x-2+100 * (x+1)+/kloc-0+.
simplify
424x= 1272
So: x=3
This three-digit number is 437.
7. Three classes in Grade One and Grade Three donate books to Hope Primary School. A class library 152 volumes. The number of books donated by Class Two is the average of three classes. The number of books donated by Class Three accounts for 40% of the total number of books donated by Class Three. How many books did Class Three donate?
Solution: Set up 2 classes to donate X copies.
3x= 152+x+3xX40%
3x= 152+x+6/5x
3x-x-6/5x= 152
4/5x= 152
X = 190...(2) Class
190X3=570 (Ben)
8. The distance between A and B is 365,438+0 km. An hour later, A rode a bicycle from A to B, and B rode a motorcycle from A to B. It was known that A was driving at a speed of 12km, and B was driving at a speed of 28 km. How many hours did B catch up with A after departure?
Let b catch up with equations a and b x hours after departure.
12 (x+ 1) = 28 x = 0.75 hours, or 45 minutes.