Can anyone please hammer out this idea of absolute value for me. Please.

$\displaystyle y = |2x - 3|$

using

$\displaystyle |x| = \begin{cases}x \ldots & x\ge 0 \\\\

-x \ldots & x \le 0\end{cases}$

I know its relatively simple but I just cant seem to get the ideas into my head. I know what it looks like graphically using a graphing utility but once I come to actually solve it by hand, I have no idea what to do

Please help