Computing inverse of a matrix

[DigitalSplendid]

Here is my attempt. Beyond that fail to understand how I arrange for the inverse.

 

[Steven G]

You start off with multiplying A by (a b c) and then you end up with x, y and z? Who knows, maybe you are correct! But that will depend on what x, y and z are. You can change your variables from a, b and c to x, y and z but you need to define your new variables. Say something like x = 2a +b, y= c and z = -a+b+5

 

[DigitalSplendid]

I am sorry. It should be:
a + b + c, 3a + 2b + c, 2a + b + 2c.