Posted by Anonymous on .
A message was encoded using the matrix
[7 2
3 1]
and you can decode the message 2 numbers at a time in a [1 x 2] matrix.
Here are the first four numbers:
66 21 119 35
I know it's coded row matrix times the decoder = the uncoded row matrix. (The key is A=1, B=2, etc.) I'm just not sure how to, because i tried it and got really large numbers. Help please?
thank you!

Math 
Reiny,
you will need the inverse matrix of
7 2
3 1 which is
1 2
3 7