Show A and B are equivalent and state their common rank

1 2 ________A

3 4

4 3 _________B

2 1

A and B are matrices that they are 2 by 2(I couldn't put a braket around it

What I did is I did RREF and I got the same Identity. But, that doesn't prove that they are equivalent

Also, I know the rank is 2(but is it b/c number of nonzero row?-explain for me)

I thank you all in advance,

thank you