xác định đầu vào và đầu ra của bài toán ''Tìm số lớn nhất trong dãy n số tự nhiên cho trước''?

$\left(\frac{3x}{7+1}\right):\left(-4\right)=\frac{-1}{28}$

$\frac{3x}{7+1}=-\frac{1}{28}\cdot \left(-4\right)$

$\frac{3x}{7+1}=\frac{1}{7}$

$\frac{3x}{8}=\frac{1}{7}$

$3x=\frac{\left(1\cdot 8\right)}{7}$

$3x=\frac{8}{7}$

 $x=\frac{8}{7}:3$

1. The people here are ______________

       A. friendly              B. delicious          C. polluted           D. long

2. He likes playing table tennis, ______________he can’t play it.

       A. and                     B. but                             C. so                     D. or

3. If you _________  these bottles, you will save a lot of money.

       A. uses                    B. reduces            C. reuse                D. reused

4. I think “Tom and Jerry is the best ______________ .

      A. news                    B. sport                C. newsreel           D. cartoon

5. In the future, we won’t go on holiday to the beach but we ________ go on holiday to the moon.

      A. must                    B. can’t                C. might               D. won’t

6._____________the air is cleaner, people will have less breathing problems.

      A. Unless                 B. When               C. If                     D. Because

7. They couldn’t go on a picnic ______________the weather was bad.

      A. because                B. when                C. but                  D. or

8. We will have a robot to ___________ the children.

      A. look for               B. look at             C. look after                   D. look up

9. I want to watch the cartoon _________ it is funny and simple.

      A. but                      B. so                    C. although           D. because

10. They  ______  badminton next week.

     A. will play               B. to play             C. playing            D. plays

11. This is my house . This house is ________
     A. my                       B.  me                  C. mine                 D. I
12. What can we do to__________ air pollution?
     A. reduce                   B. reuse               C. wash                D. recycle
13. Don’t forget to __________ the lights when you go out of the classroom.
      A. turn on                 B. turn off            C. close               D. shut down
14. Hue is an interesting city. I love ______food.
     A. it                          B. its                    C. it’s                  D. it is
15. Who is your favorite _______? He is Pelé

     A. farmer                            B. teacher             C. singer              D. sportman
16. You should put the food in a reusable box __________ plastic bags.
     A. By                        B. Instead of         C. Because of       D. Without
17. If we use __________ paper, we will save a lot of trees.
     A. Fewer                             B. Less                C. More                D. Much

18.     Could you turn _________ the volume please? I can’t hear that singer very well.

     A. up                    B. down               C. on                    D. off

19.     I like watching the news _________ I want to know what is happening around the world

     A. and                  B. so                     C. but                   D. because

20. _______air and the environment will be more polluted someday.

     A. a                      B. an                    C. the                   D. one

1D

2D

3D

4D

5C

6D

7D

8D

 Nga's favourite sport is badminton