Hello, I have a homework problem that I am not seeing quite well. Please help somebody.

1) Let A be a 4 by 4 matrix. If

adjoint A=

2 0 0 0

0 2 1 0

0 4 3 2

0 -2 -1 2

find A.

Answer from back of the book:

A=

1 0 0 0

0 4 -1 1

0 -6 2 -2

0 1 0 1

*I have no clue on how to go from Adjoint A to A.