X + 20 = 50 - 10

X + 20 = 40

X         = 40 - 20

X         = 20

a=1 (thuộc N)

điên con mẹ mày
 

viết tiếng anh theo chủ đề 'image that you have a friend in another country and you would like to invite him or her to visit the village . write a brief introduction to attract him to visit your village'