Nếu hai người cùng tham gia một công việc thì sau 2 giờ là xong. Nếu người thứ nhất làm nửa công việc sau đó người thứ 2 làm một mình nửa công việc còn lại thì toàn bộ công việc được hoàn thành trong 4 giờ 30 phút. Hỏi mỗi người làm một mình thì cần bao nhiêu lâu

Các câu hỏi liên quan

What's your name? * My name's Ngoc Chau 2. What's class are you in? * 5/1 5/2 5/3 5/4 5/5 5/6 Tùy chọn 7 3. You need a lot of money to buy this, It's... * cheap expensive popular 4. Robots do not have these. * hands legs feelingS 5. Cars go along this. * road modern expensive 6. Your bike is more ... than mine * cheaper cheap modern 7. This house is the ... beautiful. * Hình ảnh không có chú thích more less most 8. In the fable" The Ant and the Grasshopper". The grassopper played a guitar. * yes no 9. The grasshopper could not find any food in ... * summer winter autumn 10. A big ship that travels around in space. * a spaceship a plane a rocket 11. The astronaut will ... space food through a tube. * eats eating eat 11. Will they travel by plane to the moon? * No, they will. No, they won't. No, they aren't. 12. It gives us light and keep us warm. * moom star sun 13. We will look at the star ... * next week last week last night 14. These shoes are ... than my shoes. * good gooder better 15. There are six ... in my family. * member people person 16. Heavy rain and thunder.____________ * windy rainy storm 17. It's long and thin and carries astronauts.__________ * plane rocket helicopter 18. When a bed or a chair makes you feel relaxed, it is this._________________ * soft mordern comfortable 19. My brother is ________ than my mom. * taller tallest shortest 20. My new schoolbag is more _________ than yours. * cheaper expensive bigger 21. I will take a lot of photos _____________. * last year yesterday next vacation 22. _______ you read a history book tomorrow? * Do Will Are