Morgan Stanley reported the following for 2023: total revenue of $70 billion, cost of goods sold of $35 billion, operating expenses of $25 billion, interest expense of $4 billion, and tax expense of $6 billion. The total assets were $160 billion, and total liabilities were $90 billion.

1. Calculate the operating profit margin.
2. Determine the net profit margin.
3. Compute the interest coverage ratio.
4. Determine the debt-to-equity ratio.