57. Facebook, Inc. reported the following financial information for the year ending December 31, 2023:
58. 
    
    • Total Revenue: $150 billion
    • Cost of Goods Sold (COGS): $30 billion
    • Operating Expenses: $70 billion
    • Other Income: $10 billion
    • Tax Expense: $20 billion

a) Calculate the gross profit. b) Determine the operating profit. c) Compute the net profit before tax. d) Calculate the net profit after tax, assuming a tax rate of 15%.