Final answer:
The net interest margin for ABC Bank, which is calculated as the difference between interest revenues and expenses divided by the average earning assets, comes out to be 6%.
Step-by-step explanation:
The net interest margin (NIM) for ABC Bank can be calculated using the formula: NIM = (Interest Revenues - Interest Expenses) / Average Earning Assets. In this case, ABC Bank's interest revenues are $50 million and its interest expenses are $20 million. The average earning assets are assumed to be its total assets, which are $500 million. Therefore, the calculation would be ($50 million - $20 million) / $500 million, resulting in a NIM of 6%.