Any explanation you could give would be awesome! (Class is entirely self paced which is rather hard for learning)

3. Use the following data on a bank (in Smillions) to answer the questions: Reserves 18.9 Loans 150 Security 31.3 Checkable deposit 180 Bank capital 20.2 Required reserve ratio 10% a. Write out the bank's balance sheet. What is the bank's excess reserve? b. Suppose the bank sells $5 million of securities to the Fed. What is the bank's excess reserve now