I you want to know how to work out a problem step by step, visit quickmath.com.
QuickMath is an automated service for answering common math problems over
the internet.
Think of it as an online calculator that solves equations and
does all sorts of algebra and calculus problems - instantly and automatically!
When you submit a question to QuickMath, it is processed by Mathematica, the
largest and most powerful computer algebra package available today. The answer
is then sent back to you and displayed right there on your browser, usually
within a couple of seconds.
Best of all, QuickMath is 100% free !