ai giúp mình giải theo cách tự luận vs ạ

mng giải giúp em đề này ạ trừ bài 3 ra ạ

Tìm a b c biết a) a: b: c=2:4:5 và 2a -b+c=7 b)a/2=b/3=c/4 và a^2-b^2+2c^2=180

Ai giải giúp câu 6 vs ạ phần mình bôi đen r á

bài1.1 thửa ruộng hình bình hành có tổng số đo cạnh đáy và chiều cao là 96m.Chiều cao kém cạnh đáy 12m;trên thưa ruộng đó người ta trồng rau .tính a; diện tích thưa ruộng hình bình hành b;cứ 4m vuông thu được 24kg rau.số rau thu được trên thưa ruộng đó là bao nhiêu ki -lô-gam .

Vẽ sơ đồ và cho biết vai trò của sụn tăng trưởng

mọi người giúp mình với mình tặng 50 điểm nha The first traffic control device appeared near the British House of Parliament at the intersection of George and Bridge Streets. The device was made in response to the desire by a Select Committee to use railway signals on highways. The device had lights and it used arms which extended outwards. It was operated manually by a police officer. The signal was 22 feet high and crowned with a gas light. The light was called semaphore and had arms that would extend horizontally that commanded drivers to "Stop" and then the arms would lower to a 45 degrees angle to tell drivers to proceed with "Caution". At night a red light would command "Stop" and a green light wouldmean use "Caution".The man behind this new and different invention was John Peake Knight a railroad engineer. The main reason for the traffic light was that there was an overflow of horse-drawn traffic over Westminster Bridge which forced thousands of pedestrians to walk next to the house of Parliament. But Knight's invention was not to last long. After only a month of use the device exploded and injured the police officer who was operating the light. In the first two decades of the 20th century semaphore traffic signals, like the one in London, were in use all over the United States with each state having its own design of the device. One good example was from Toledo, Ohio in 1908. The words "Stop" and "Go" were in white on a green background and the lights had red and green lenses illuminated by kerosene lamps for night travelers and the arms where eight feet above ground. Controlled by a traffic officer who would blow a whistle before changing the commands on this signal to help alert travelers of the change, the design was also used in Philadelphia and Detroit. The example in Ohio was the first time America tried to use a more visible form of traffic control that evolved the use of semaphore. The device that was used in Ohio was designed based on the use of railroad signals. 1. What was the main purpose of making the first traffic control device? …………………………………………………………………………………………………………… 2. What was the light operated manually by a police officer called? ……………………………………………………………………………………………………………… 3. Why wasn't John Peake Knight's invention to last long? ………………………………………………………………………………………………………… 4. How tall were the arms of the traffic lights used in Ohio in 1908? ……………………………………………………………………………………………………………… 5. The Westminster Bridge is in . ………………………………………………………………………………

Một mảnh vườn hình chữ nhật có nửa chu vi là 76m. Chiều rộng bằng 60% chiều dài. Tính diện tích mảnh vườn đó. Người ta sử dụng 8% diện tích mảnh vườn làm lối đi. Tìm diện tích lối đi. Bài giải

1.Quốc gia nào ở Trung và Nam Mỹ có sản lượng cá vào bậc nhất thế giới A. Pê- ru B. Cô- lôm- pi -a C. Chi lê D. Ê- cua -do 2. hình thức sở hữu Nông Nghiệp Đại Điền Trang có tên gọi là gì? A. La - ti-đi-a B. Mi -ni-fun-đi-a C. La-ti-fun-đi-a D. Mi-ni-đi-a

8Choose the best answer: They got on quite well despite the language............................... A. communication B. breakdown C. barrier D. telepathy 9Choose the best answer: His mother is so worried now. The only thing he ........................ with is his smart phone. A. interacts B. speaks C. sends D. uses 10Choose the best answer: Send a ..................... messaage to 9354 to vote for your idol. A. text B. cyber C. multimedia D. snail 11Choose the best answer: A lot of waste from hotels and factories is .................................... into the lakes. A. contaminated B. dumped C. affected D. polluted 12Choose the best answer: I posted a question on ............................ board and got many interesting answers. A. cyber B. media C. Internet D. message 13Choose the best answer: Ann and Tom have never met ................ before. They only chat on Facebook. A. eye-to-eye B. head-to-head C. face-to-face D. should-to-shoulder 14Choose the best answer: The Internet is one of the most ............................ means of communication. A. effect B. effective C. affect D. affected 15Choose the best answer: There are a lot of ways to ............................. through the Internet. A. communicated B. communicative C. communication D. communicate 16Choose the best answer: If I ................... a lot of money, I ............................... to London. A. had/ will travel B. have/ travel C. had/ would travel D. had had/ would travel 17Choose the best answer: The original London bridge ................................. in the Great Fire in 1666. A. destroyed B. had been destroyed C. had destroyed D. was destroyed 18Choose the verbs in brackets in the correct form. You (not get) ......................what you want unless you work harder. A. don't get B. won't get C. didn't get 19Choose the verbs in brackets in the correct form. The teacher said this water (be) .................... too contaminated to be used. A. was B. is C. has been 20Choose the verbs in brackets in the correct form. Development in medical science (help) ................... people live longer in the future. A. would help B. must help C. will help 21Choose the verbs in brackets in the correct form. If we had flying cars now, we (solve) ............... the problem of traffic jams. A. can solve B. could solve C. will solve 22Choose the verbs in brackets in the correct form. Anna said she (be) ................... going to leave when Tom came. A. is B. were C. was