1.Why do you go to Da Lat festival every year?

2.How often is the sea festival help your country?

3.What did you take when you go to Rio Carnival last year?

4.When is halloween help?

5.What do the Internatinal Fireworks take place ?

AB=AM+MC+CN+NB mà AM=MC ; CN=NB nên AB=2(MC+CN)

ta có; MN=MC+CN từ đó MN=AB/2=a/2