Many credit cards use a similar formula for the minimum payment, which is the new balance (if less than $25), or else the greater of $25 or 1% of the new balance (usually including interest and late fees), plus the interest billed, rounded down to the nearest dollar. Any late fees are then added on to this calculated amount. The actual interest, applied with daily compounding, is the APR/365, so the amount of interest owed for a month depends on the number of days in the month. For simplicity, you should use a uniform monthly rate of APR/12.) (Requires spreadsheet.) Suppose that your credit card has an APR of 18%, but you screw up and miss the first payment, incurring a $39 late fee and an increase to a penalty APR of 29.99% - call it 2.5% per month. (a) How many months of paying your bill on time will it take to pay off the balance of $3117.83 by making the minimum payment each month (on time!)? (You must pay the $39 late fee the first month, over and above the minimum payment on the $3117.83 and one month's