Invest or pay off credit card?

Maybe it was the financial planner on CNBC, a casual conversation with a friend, or just the small voice inside, but something has caused you to keep asking yourself the same thing: should I pay off my debt or start investing? This question, perhaps more than any other, has plagued investors for generations. Ironically, it is one that can be easily decided by using a bit of simple math.
(Source: About.com Investing for Beginners)