2 x + 2 y = 8and subtract it from the second equation, like this: The result is one equation in the one unknown, y. The other unknown, x, has been eliminated. Solving this equation yields y = 0.4.
{ x = 3.6, y = 0.4 }.(Note that we could have found x without backsubstitution if we had subtracted 3 times the first equation from the second equation, since this eliminates y.)
The Elementary Row Operations (E.R.O.’s) are:

The Gauss and the GaussJordan Elimination Procedures We transform one column at a time into the desired form, either Gauss or GaussJordan. The column presently being transformed is called the pivot column. We proceed systematically, letting the pivot column be the first column, then the second column, etc. until the last column before the vertical line of the augmented matrix. For each pivot column, we do the following two steps before moving on to the next pivot column:
When all the columns before the vertical line have been transformed using the GaussJordan procedure the augmented matrix will be in GaussJordan form and we simply read the solution from the column to the right of the vertical line. 
{ x = 7, y = 5, z = 3 }.
{x = 49, y = −18, z = 8}.
Algebra Coach Exercises 