Use the inverse of the matrix 
to decode the cryptogram:
51 72 27 38 27 36 38 57 59 81 42 61
Divide the message into groups of two (the matrix A is a 2 x 2) to form the coded row matrices and multiply each coded row matrix by A-1 on the right.
Use the inverse of the matrix to decode the cryptogram:
51 72 27 38 27 36 38 57 59 81 42 61
Divide the message into groups of two (the matrix A is a 2 x 2) to form the coded row matrices and multiply each coded row matrix by A-1 on the right.
Find A-1
Divide the message into groups of two (the matrix A is a 2 x 2) to form the coded row matrices and multiply each coded row matrix by A-1 on the right.
Thus, the message is:
