ABC Corporation's financial statements show the following:

• Cash: $60,000
• Accounts receivable: $35,000
• Inventory: $30,000
• Total current liabilities: $50,000
• Total assets: $300,000
• Total liabilities: $120,000
• Net income: $40,000

Compute: a) Quick ratio b) Inventory turnover ratio c) Return on equity d) Operating profit margin