Tham khảo :

In a certain village, there are two grandparents, even though they are old, but still have not had a pimple. One day, the old woman came back from the field and found that there was a very large mark on her leg so she tried it with her hand. She went home immediately and became pregnant. Twelve months later, she gave birth to a son. Even though she is three years old, she still cannot speak and smile. Shortly after, An enemy invaded our country. The king wants to find someone who has the talent to fight the enemy and save the country. It was strange that the messenger came to Giong village, the boy suddenly said: “I invite the messenger here”. He sent envoys to the king to buy an iron horse, an iron whip and an iron armor plate to fight the enemy. Since that day, the boy grew too fast, could not eat much, did not wear any clothes. The enemy arrived, the messenger sent the iron horse, the iron whip and the iron armor, the young man had grown himself to become a hero to defeat the enemy. After fighting the enemy, he took off his iron armor and flew to the sky. To commemorate the merits of Thanh Giong, the king set up a temple in his hometown and named it Phu Dong Thien Vuong.

đồi \(18m=180dm\)

cưa tất cả các khúc gỗ \(9dm\) thì được 

\(180 : 9 = 20\)

cần cưa số khúc gỗ là :

\(180 : 9 - 1 = 19\) (khúc gỗ )

thời gian cưa \(1\) khúc gỗ là :

\(285 : 19 = 15\) (phút)

đ/s....

It's on the right , opposite the head teacher's ofice.

8, Viết PTHH của H2O với các chất: CaO, BaO, Na2O, K2O, P2O5, SO3

7, Viết PTHH của O₂ với các chất: Al, C, P, Mg, Cu, Na, K, Zn, Ba

6, Hoà tan 14,4 gam muối ăn vào 400 gam nước ở 20^oC thì được dung dịch bão hoà. Hãy tính độ tan của muối ăn ở nhiệt độ đó?