You may or may not have seen this before -- it depends on where you took your last Algebra class.
First, I need to tell you about determinants. We'll be using these to solve systems.
Say you've got a 2 x 2:
We can make something called a "coefficient matrix":
A matrix is just a grid of numbers with brackets around them. (Remember that a coefficient is the number in front of the variable... x = 1x, so the coefficient is 1.) (We'll learn more about these matrix things in the next chapter.)
We've got rows and columns of the matrix: