Exxon Mobil Corporation had the following financial data for the year ending December 31, 2023:

• Total Assets: $800 billion
• Total Liabilities: $400 billion
• Shareholders' Equity: $400 billion

a) Calculate the debt-to-equity ratio.

b) Determine the return on assets (ROA), assuming the net income for the year is $60 billion.

c) Compute the return on equity (ROE), assuming the net income for the year is $60 billion.