Ellen has maxed out her credit card at $20,000 and vows not to make any other credit card purchases. Her credit card company charges 1.5% interest per month, and the minimum monthly payment is all interest due plus 2% of the principal balance. How much of the balance can Ellen pay down if she pays the minimum payment only for 4 months? Round the answer to the nearest cent. After 4 months, Ellen would have paid off $