So I'm trying to find the inverse of the matrix:

[2 4 2]

[2 5 2]

[0 2 -1]

I've gotten up to this bit:

[1 0 5 | -1/2 -2 0]

[0 1 -2| 1/2 1 0]

[0 0 -3| 1 2 -1]

I can't figure out how to get a 1 on the bottom right corner or the remaining two 0's. Help would be appreciated!