B

c

A

B

12cm2

Mình cần nêu phần cảm nghĩ của bản thân ở phần kết bài nhé!!!

45.(-100) = -(45.100) = -4500

It's a good idea if we help our friends to do the hard exercise. We can also improve our skill by answering those questions, too.

But I think that's not nice if we help our friends to do their exams and tests. They should do by themselves.