DEF Ltd. provides the following financial data:

• Total assets: $600,000
• Total liabilities: $200,000
• Common stock: $150,000
• Retained earnings: $100,000
• Net income: $80,000
• Total revenues: $400,000
• Total expenses: $320,000

Determine the following: a) Debt ratio b) Earnings per share c) Return on investment d) Asset turnover ratio