48. Pfizer Inc. had the following financial data for the year ending December 31, 2023:
49. 
    
    • Total Assets: $400 billion
    • Total Liabilities: $150 billion
    • Shareholders' Equity: $250 billion

a) Calculate the debt-to-equity ratio. b) Determine the return on assets (ROA), assuming the net income for the year is $40 billion. c) Compute the return on equity (ROE), assuming the net income for the year is $40 billion.