The following data relates to a bank, Tolland Union. The bank earned $3.530B of in interest revenue and paid $2.671B  in interest expense last year. There were also fees and points earned from loans and loan origination, increasing income of $24M. 

During that year, the bank generated net earnings of $660M. The bank has $24.9B of interest earning assets at year end ($22.3B prior  year), AND total assets of $31.5B at year end ($30.2B prior year). The shareholders' equity is $5.9B at year end ($5.1B prior year).

a. What is the net interest margin using earning assets? 

b. What is the bank's return on assets (ROA)? 

c. What is the bank's return on equity (ROE)?