Mary and Mark both have $400 of debt on their credit cards. Each month, they are charged a 20% annual interest on their cards' outstanding balances. So when Mary and Mark make payments, part of each payment goes to paying interest and part goes to the principal. Mary and Mark promise themselves they will not charge any more purchases until they have completely paid off their credit card balances. The cards each require a minimum monthly payment of 3% of the balance owed, or $10, whichever is higher. Mary will pay the minimum but Mark will pay an extra $15 per month in addition to the minimum payment. Mary pays the minimum payment of $ . This will make the new balance $ , the amount that will go toward paying the balance is $ Mark pays the minimum plus $15, so his payment would be $ interest charge (found in Part A) is $ the balance is $ and since the interest charge is $ 1 and since the the amount that will go toward paying This will make the new balance $