Kim's credit card was not paid in full last month so she will pay a finance charge

Question:

Kim's credit card was not paid in full last month so she will pay a finance charge this month. She had an average daily balance of $d during this billing period, which had 31 days. The APR was p%.
a. Express algebraically the APR as an equivalent decimal. b. Express algebraically the monthly percentage rate as an equivalent decimal.
c. Express the finance charge algebraically.