Hello, can anyone help me with this problem, Thanks a lot!!

Problem 10 (10 points). Whenever B can be derived from A by a combination of elementary row and column operations, we write A N B, and we say that A and B are equivalent matrices. Since elementary row and column operations are left-hand and right-hand multiplication by elementary matrices, we can say that A N B 4:} FAQ = B for noneingular P and Q.Fir3t show if A is m x n such that rank(A) = r, then A N Nr = (I; 3) where N1. is called the rank A 0 normal form for A. Using above denition explain why rank( (0 B )) = rank(A) + rank(B)