1. Let's go to Nha Trang City
-> What about going to Nha Trang City
2. What is the price of the watch?
-> How much is the watch?
3. My father is a worker in Thang Long Industrial Park
-> My father works for Thang Long Industrial Park
4. There are no battles on the shelf
-> There aren't any battles on the shelf
5. Lan wants to play chess in her free time
-> Lan enjoys playing chess in her free time

x=77

ai k mk mk 

k alij cho !

các bạn giải bằng cách dễ hiểu nhất nhé

xin các bạn đó

^_^

\(S=1.2+2.3+...+38.39\)

\(\Rightarrow3S=1.2\left(3-0\right)+2.3\left(4-1\right)+...+39.40\left(41-38\right)\)

\(\Rightarrow3S=1.2.3-0.1.2+2.3.4-1.2.3+...+39.40.41-38.39.40\)

\(\Rightarrow S=\frac{39.40.41}{3}\)

\(\Rightarrow S=21320\)

3 + 4 + 5 + 5 + 6 + 7 + 8 + 10 + 10 + 3 + 4 + 5 + 5 + 6 + 7

= (3 + 7) + (3 + 7) + (4 + 6) + (4 + 6) + (5 + 5) + (5 + 5) + 10 + 10

=     10   +    10    +    10    +     10   +     10   +    10    + 10 + 10

=     80

= 1410

= 1263