please explain:

If Param's average daily balance on his credit card for the previous month was $6.3, his grace period 20 days, billing period 30 days, interest rate 4.9 percent calculated daily (not compounded), and he paid the full balance 7 days late, what would be the amount of interest owing on the day of payment? (Submit answer to two decimal places (include pennies) and DO NOT add a negative (minus) sign.)