Hello, landlord, 1, a reservoir has a certain storage capacity, and the river flows into the reservoir evenly every day. 5 pumps can pump continuously for 20 days: 6 identical pumps can pump continuously 15 days. How many identical pumps do you need if you want to pump for 6 days? The amount of water pumped includes constant water storage and daily water injection. Suppose 1 pump pumps 1 serving a day, the former pumps 100 (5*20) and the latter pumps 90 (6* 15). Why does the latter smoke less 15? Because the river water has been injected for less than 5 days (20- 15), it is known that the river water can be injected with 2 portions of water every day (10/5). At this time, it can be calculated that the amount of water stored in the reservoir is 60. According to the meaning of the question, adding 12 parts of river water (6*2) will take 6 days to extract 72 parts of water. 57 seconds later, the train passed in front of him. It is known that when the train whistles, it is1360m away, and the speed of sound in the air is 340m per second. Find the speed of the train. It takes 1360/340=4 seconds for the sound to reach his ears. So the train actually ran 1360m, and it took 57+4=6 1 second, so the train speed was 1360/6 1 meter per second, that is1360/61* 60. At the age of kloc-0/7, I noticed that the age difference between A and B is unchanged, so B is 17+a, so C is twice that of B, which is 2×( 17+a). According to the age difference between A and C, we can get: 38-A = 2× (65438+A). B is 14 years old, C is 38 years old, and the total is 7+ 14+38=59 years old, (113-59) ÷ 3 =18. In 18 years, the sum of their ages will be 60. (2000- 1600) ÷ 2000 = 20% A: 20% reduction. 5. There is an air conditioner, the original price is 1600 yuan. After the price increase, it sold for 2000 yuan, which increased by a few percent. (2000-1600) ÷1600 = 25% A: It increased by 25%. 6. There is a TV with the original price of 1200 yuan, which is lower than that of 300 yuan. How many percent has the price dropped? 300 ÷ 1200 = 25% A: It decreased by 25% 7. There is a kind of disinfection cabinet, the original price is 2400 yuan, which has increased by a few percent in 400 yuan, by 400 ≈ 2400 ≈ 16.6% A: by16. What percentage has this year increased compared with last year? 24+6=30 (1) 30 ÷ 24 =125%125%-100% = 25% 9. There is a park, the original ticket to 80 yuan. How much can you save per ticket if you give a 20% discount during the National Day? What's the equivalent of a price reduction? 80×0.8=64 (yuan) 80-64= 16 (yuan) (80-64) ÷ 80 = 20% A: it can save 16 yuan, which is equivalent to a price reduction of 20% 10. Nanshan Primary School covers an area. How many square meters are there in the teaching building and road? 8000× 65% = 5200 (square meters) 8000-5200=2800 (square meters) Answer: Nanshan Primary School has a green area of 5200 square meters, with 2800 square meters of teaching buildings and roads. .................................. wishes the landlord a happy New Year! ~ ~ ... I'm glad to answer your question. Please keep asking questions. Thank you for your timely adoption! ............. (and I hope you can come to me for help next time if you have any new problems).