Hiệu số phần bằng nhau là

   $5-3=2$ ( phần )

Số bé là 

  $78÷2\times 3=117$ 

Số lớn là

  $117+78=195$

Pho is one of the Vietnamese traditional food. The most delicious and typical brand of Pho in Vietnam is Ha Noi Pho with wonderful flavor. Pho is made from rice noodles, beef or chicken and other spices. Pho is a noodle soup; therefore, it’s better when being added with beansprout. Eating Pho with family not only reflects Vietnamese tradition but also creates cozy atmosphere. At weekends, my friends and I usually go to a cafeteria to enjoy Pho because Pho is served at many restaurants in Vietnam. There are two main kind of Pho: noodle soup with beef and sliced chicken, both of them are delicious and high nutrients. Pho is favorite food of almost Vietnamese and often served as breakfast. Moreover, Pho is popular in international market for its pleasant taste and reasonable price. Foreign tourists visit Vietnam and they really like the taste of Pho here. I am very proud of it. In near future, I hope Pho will be more famous in other countries so that foreigners can enjoy this cuisine and understand about Vietnamese culture.
 

Bài giải :

Thời gian tàu thủy đó đi từ A đến B là:

    7 giờ 45 phút - 6 giờ 30 phút= 1 giờ 15 phút

     Đổi 1 giờ 15 phút = 1,25 giờ

Vận tốc của tàu thủy là:

    30 : 1,25 = 24 (km/giờ)

      Đáp số 24 km/giờ

Pho is one of the Vietnamese traditional food. The most delicious and typical brand of Pho in Vietnam is Ha Noi Pho with wonderful flavor. Pho is made from rice noodles, beef or chicken and other spices. Pho is a noodle soup; therefore, it’s better when being added with beansprout. Eating Pho with family not only reflects Vietnamese tradition but also creates cozy atmosphere. At weekends, my friends and I usually go to a cafeteria to enjoy Pho because Pho is served at many restaurants in Vietnam. There are two main kind of Pho: noodle soup with beef and sliced chicken, both of them are delicious and high nutrients. Pho is favorite food of almost Vietnamese and often served as breakfast. Moreover, Pho is popular in international market for its pleasant taste and reasonable price. Foreign tourists visit Vietnam and they really like the taste of Pho here. I am very proud of it. In near future, I hope Pho will be more famous in other countries so that foreigners can enjoy this cuisine and understand about Vietnamese culture.

Số sách của thư viện sau một năm so với ban đầu chiếm số phần trăm là:

           100% + 20% = 120%

Số sách của thư viện sau năm thứ nhất là:

           6 000 $\times$ 120 : 100 = 7 200 (quyển)

Số sách thư viện sau hai năm là:

                 7 200 $\times$ ( 100% + 20%) = 8640 (quyển)

                              Đáp số: 8640 quyển

Đáp án là C: Các phần tử không khí dao động tới lui theo hướng truyền âm. 

Khi ta đánh trống mặt trống dao động làm cho lớp không khí tiếp xúc với mặt trống dao động Lớp không khí đó làm cho lớp không khí kế tiếp giao động cứ như thế, động được truyền đến tai ta làm cho màng nhĩ dao động làm cho ta nghe được âm thanh $.$

I learn English by speaking it everyday

 Mai learns English by reading comic books in her free time

 We learn English because we want to talk with our foreign-friends

 Why does your father learn English?

 My favourite subject is English

 How often do you have English, Mai?

 I have English four times a week

 My sister always watches English cartoon on television

17,86

650 x 34 + 34 x 2 x 135 + 34 x 80 

= 650 x 34 + 34 x 270 + 34 x 80

= 34 x ( 650 + 270 + 80 )

= 34 x 1000

= 34000

650 x 34 + 34 x 2 x 135 + 34 x 80 

= 650 x 34 + 34 x 270 + 34 x 80

= 34 x ( 650 + 270 + 80 )

= 34 x 1000

= 34000