1. The problem statement, all variables and given/known data
For part 1 I solve the problem and I got the follow equation and results:

.25x+.10y+.05z=1.15
x+y+z=9
-2y+z=0

The solution is x=3, y=2, z=4

Now I have to solve this by hand with the equation in matrix form using elimination matrix

2. Relevant equations

EAx = Eb

3. The attempt at a solution

A=[.25 .1 .05; 0 -2 1; 1 1 1];
B= [ 1.15; 0; 9]

Using Matlab I can solve it like this X= inv(A)*B = x=3, y=2, z=4 but that is not what he wants

to me the first elimination matrix is E= [1 0 0; 0 1 0; -1 0 1] but is not eliminating anything.
This may help some but I don't see how:
http://www.gregthatcher.com/Mathematics/GaussJordan.aspx" [Broken]

How do I solve this by hand and then input it into matlab?