Melinda just charged $2, 100 on a laptop on her credit card that charges an annual interest rate of 21%. Melinda can only afford $100 each month to pay down her credit card debt, but she is not going to charge anything else on her card until she pays off this debt. Let Pn denote her credit card debt n months after buying the laptop. Write a recursive sequence that models her credit card debt: Pn= Po =