đánh giá nghệ thuật quân sự nhà lê mình cần gấp

Vì E là trung điểm của AB

F là trung điểm của AC

=>EF là đường trung bình của △ABC

=> EF=1/2BC và EF//BC

1. My sister cooks meals everyday.

2. My mother cleaned the floor yesterday.

3. My friend writes ten emails for 2 hours every day.

4. My father paints our house whenever Tet comes.

5. My sister bought groceries at the supermarket.

6. My brother uses a pencil to draw beautiful pictures.

7. They finished all their word at night.

8. Every morning, I do many morning exercises

9. We plant trees and flowers in the garden every summer.

10. We study informatics at school.

a, Tổng số Nu: 5000:20%= 25000

b,L= 3,4 × (25000:2)=42500

x-y=9

x=9+y ;y=x -9

(4x-9/3x+y)-(4y+9/3y+x)=(4x-9/3x+x-9)-(4y+9/3y+y+9)=0