Apple Inc. reported the following financial information for the year ending December 31, 2023:

• Total Revenue: $200 billion
• Cost of Goods Sold (COGS): $80 billion
• Operating Expenses: $50 billion
• Other Income: $10 billion
• Tax Expense: $30 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 20%.