20 years since I was in high school. How do I break this down? 
$-5 = 2x + 5$

I want to "re-start" my mathematical education.  I am needing it more and more at work.  A co-worker asked me to break that down (he couldn't remember either).
Where should I start?  What books?  
Thanks!

This is an equation, because it says "Left hand side = Right hand side".
Think ow an equation as a scale in perfect balance. Now you have to rearrange everything, without destroying the balance, so that the $x$ will appear at one side alone. Because then you know what $x$ is.
For example, if you take away the same amount from both sides, the scale will remain in balance. So, let us take away $5$ from both sides, and we end up with 
$-10 = 2x$
Now, if the scale is in balance now, it will remain in balance when we make each side half as big, because if two things are equal, then their halves are equal as well. This leaves us with
$-5 = x$
The scale is in balance, on the left side we have a $-5$ and on the right side we have $x$. Therefore, $x$ has to be $-5$.
Now, to re-start your education: The problem above is elementary algebra, so I'd pick up with an algebra book that starts from the beginning. Something like "Math for Dummies" might be a nice idea as they are fun to read.
