Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Matrix Operations
Twenty problems present a variety of practice with matrix operations. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View Solution" button to check...
Paul Dawkins
Paul's Online Notes: Augmented Matrices
Here are good examples of the Gauss-Jordan elimination method to solve systems of equations.
Wolfram Research
Wolfram Math World: Gaussian Elimination
This site provides an example of Guassian Elimination and concludes with a specific example.