Margie has had a tough month. First, she had dental work that cost $700. Next, she had her car transmission rebuilt, which cost $1,400. She put both of these unexpected expenses on her credit card. If she does not pay her credit card balance when due, she will be charged 21% interest. Margie has $15,000 in a money market account that pays 3% interest.

How much interest would she pay (annualized) if she does not pay off her credit card balance? How much interest will she lose if she pays the balance due out of her money market account? Should she pay off the balance?