The kind-hearted man gave me a solution to the equation

The kind-hearted man gave me a solution to the equation

34×4
45×3
56×21
34×41
22×11
22×90
56×98
67×76
45×89
43×21
23×99
34×13
42×76
65×15
25×25
26×26
72×34
33×88
56×98
45×17
13×17
12×81
11×99
9×12
123×5
34×91
19×7
13×16
13×125
8×78
9×17
4×32
23×81
21×9
12×65
33×88
99×7
32×12
34×9
12×12
13×13
14×14
15×15
16×89
17×76
56×91
16×19
12×89
15×91
50×89
24×87
24×24
26×17
14×88
15×65
16×88
17×17
18×19
19×31
30×98
45÷3
56÷7
56÷16
78÷12
56÷14
42÷6
125÷5
128÷2
123÷3
87÷3
72÷9
77÷11
121÷11
128÷4
16÷4
129÷3
135÷5
135÷15
65÷13
77÷11
144÷12
196÷14
256÷16
88÷8
72÷9
72÷2
99÷9
1. 125 apple trees are planted in an orchard, and the number of pear trees is 20 less than 4 times of apple trees. How many trees are planted in this orchard?
2. A section of road is 324 meters long, 240 meters have been repaired, and the rest is planned to be completed in 4 hours. How many meters per hour on average?
3. Hongguang printing company bound a batch of diary books. 960 diary books were bound in the first three days, and 420 diary books were bound in the last 16 days on average?
4. A typist can input 200 Chinese characters in 4 minutes. How many minutes does it take to input 3000 Chinese characters?
5. Three bags of flour weigh 75 kg. How many kg does eight bags of flour weigh?
6. A steel plant needs 5 tons of water to make 750 kg of steel. According to this calculation, the steel plant can save 55 tons of domestic water a day. How many kg of steel can be made?
7.5 boxes of bees can brew 375 kg of honey a year. According to this calculation, how many kg of honey can 19 boxes of bees brew a year? How many boxes of bees need to be raised to brew 1725 kg of honey a year?
8. Two grade students go to buy books. There are 48 students in the third grade, each of whom buys 2 books. In the fourth grade, each of whom buys 3 books. The total number of books bought in the fourth grade is the same as that in the third grade. How many people buy books in the fourth grade?
9. Forty workers were originally planned to build roads, but 45 workers were actually used. It was planned to build roads for 90 days, but how many days did it actually take?
10. It takes 20 minutes for Xiaohua to walk home from school and 10 minutes for him to ride a bicycle. How many meters does Xiaohua walk 45 meters per minute, and how many meters does he ride a bicycle?
11. The school bought 15 boxes of colored chalk, 50 sticks in each box, and used 10 boxes. How many sticks are left unused?
12. The first, second and third workshops of Haitian Machinery Factory each produced 6 cases of parts, 120 parts per case. How many parts are produced in total?
13. One loom weaves 21 meters in one hour, and how many meters do four identical looms weave in five hours?
14. The bus goes from Nanjing to Shanghai, 60 kilometers per hour, half of the whole journey in three hours. Because one person on the bus is ill, the rest of the journey takes two hours. How many kilometers per hour on average?
15. Master Liu processed 4255 parts in 23 days, Wang
On average, Master Liu processes 18 more parts per day than Master Liu. How many parts does Master Wang process per day?
16. A cow of Uncle Li's family eats 50 kg of grass in 10 days. According to this calculation, how many days does 155 kg of grass suffice for this cow?
17. There are 18 cruise ships in the Lakeside Park, and the daily income is 1008 yuan. According to this calculation, there are 26 cruise ships now, how much yuan will the daily income increase?
18. The factory has to process 360 parts, and Xiao Wang can finish it in 5 days. How many parts can be processed in 8 days with this speed?
19. Mingming read a story book, 20 pages a day, half of the book in five days. How many pages is the book?
20. The teacher bought 6 pens. The price of the pen is 3 times that of the ballpoint pen. The price of a ballpoint pen is 2 yuan. How many yuan did the teacher buy the pen?
21. The first workshop of agricultural machinery factory is divided into three groups to process 3420 parts, with 12 workers in each group. How many parts does each worker process on average? (solved by two methods)
22. The factory rented 10 cars to transport 480 tons of goods, and each car transported 12 times. How many tons of goods are transported by each car on average?
23. Woodpeckers can eat 645 pests a day and frogs can eat 608 pests in eight days. How many more pests do woodpeckers eat than frogs?
24. A pile of coal is 160 tons, and four trucks transport 96 tons three times. According to this calculation, how many times can four trucks transport this pile of coal?
1. A and B leave from ab at the same time. A drives 5 / 11 of the whole journey. If a drives 4.5 kilometers per hour, B drives 5 hours. How many kilometers is the distance between AB and ab?
AB distance = (4.5 × 5) / (5 / 11) = 49.5km
2. A passenger car and a freight car leave each other from a and B at the same time. The speed of the freight car is four fifths of that of the passenger car. After a quarter of the whole journey, the freight car runs 28 kilometers to meet the passenger car. How many kilometers are there between a and B?
The speed ratio of passenger cars and freight cars is 5:4
Then the distance ratio of meeting is 5:4
4 / 9 of the whole journey of freight cars when they meet
At this time, the freight car has traveled 1 / 4 of the whole journey
4 / 9-1 / 4 = 7 / 36 from the meeting point
Then the whole journey = 28 / (7 / 36) = 144 km
3. Party A and Party B travel around the city. Party A travels 8 kilometers per hour and Party B travels 6 kilometers per hour. Now they start from the same place at the same time. After meeting Party A, Party B travels 4 hours to return to the original starting point?
A / b speed ratio = 8:6 = 4:3
When we met, B made 3 / 7 of the whole journey
So 4 hours is 4 / 7 of the whole journey
So the time of a week in line B = 4 / (4 / 7) = 7 hours
4. Party A and Party B walk from place a to place B at the same time. When Party A walks 1 / 4 of the whole journey, Party B is 640 meters away from place B. when Party A walks the remaining 5 / 6, Party B walks 7 / 10 of the whole journey. What is the distance between two places?
The remaining 1-1 / 4 is 3 / 4
So the remaining 5 / 6 is 3 / 4 × 5 / 6 = 5 / 8
At this time, a total of 1 / 4 + 5 / 8 = 7 / 8
Then the distance ratio of Party A and Party B is 7 / 8:7 / 10 = 5:4
So when a takes 1 / 4 of the whole journey, B takes 1 / 4 × 4 / 5 of the whole journey = 1 / 5
Then AB distance = 640 / (1-1 / 5) = 800 meters
5. Car a and car B leave from a and B at the same time, facing each other. Car a travels 75 kilometers per hour, while car B takes 7 hours to complete the whole journey. After 3 hours, the distance between the two cars is 15 kilometers. How many kilometers is the distance between a and B?
One situation: Party A and Party B have not met yet
Car B runs 3 / 7 of the whole journey in 3 hours
A 3-hour travel 75 × 3 = 225 km
AB distance = (225 + 15) / (1-3 / 7) = 240 / (4 / 7) = 420 km
One situation: Party A and Party B have met
(225-15) / (1-3 / 7) = 210 / (4 / 7) = 367.5km
6. A, two people have to finish the road. A has to walk 30 minutes, and has to walk 20 minutes. After 3 minutes, a finds that he hasn't taken something, and it's delayed for 3 minutes. How many minutes will he walk with him?
A starts 3 + 3 + 3 = 9 minutes later than B
Consider the whole distance as unit 1
So the velocity of a is 1 / 30
Speed of B = 1 / 20
When a finished taking things and set out, B had already gone 1 / 20 × 9 = 9 / 20
Then the distance between a and B is 1-9 / 20 = 11 / 20
The speed sum of a and B = 1 / 20 + 1 / 30 = 1 / 12
Then (11 / 20) / (1 / 12) = 6.6 minutes
7. Car a and car B start from place a and travel in the same direction. Car a travels 36 kilometers per hour and car B 48 kilometers per hour. If car a starts 2 hours earlier than car B, how long does it take car B to catch up with car a?
Distance difference = 36 × 2 = 72 km
Speed difference = 48-36 = 12 km / h
It takes car B 72 / 12 = 6 hours to catch up with car a
8. Party A and Party B set out at the same time from a and B, which are 36 kilometers apart. When party a set out from a to 1 kilometer, he found that there was something in place a in the past, and immediately returned. When he went, he immediately moved from place a to place B. in this way, Party A and Party B just met at the end of a and B. He also knew that Party A walked 0.5 kilometers more than Party B per hour, and asked for the speed of Party A and Party B?
A actually walked 36 × 1 / 2 + 1 × 2 = 20 km when they met
B walked 36 × 1 / 2 = 18 km
Then a walks 20-18 kilometers more than B
So the time to meet is 2 / 0.5 = 4 hours
So the speed of a = 20 / 4 = 5 km / h
Speed of B = 5-0.5 = 4.5km/h
9. At the same time, the two trains run from the two places with a distance of 400 kilometers. The passenger trains run 60 kilometers per hour, and the freight trains run 40 kilometers per hour. After running for a few hours, the two trains meet each other with a distance of 100 kilometers?
Speed sum = 60 + 40 = 100 km / h
There are two situations,
No meeting
So it takes time = (400-100) / 100 = 3 hours
Have met
Then it takes time = (400 + 100) / 100 = 5 hours
10. A drives 9 kilometers per hour, B drives 7 kilometers per hour. The two travel at the same time at a distance of 6 kilometers. A few hours later, the distance is 150 kilometers?
Speed sum = 9 + 7 = 16 km / h
Then after (150-6) / 16 = 144 / 16 = 9 hours, the distance is 150 km