Calculate Return on Investment (ROI) from the following details: Net Profit after Tax ₹ 6,50,000; Rate of Income Tax 50%

Calculate Return on Investment (ROI) from the following details: Net Profit after Tax ₹ 6,50,000; Rate of Income Tax 50%; 10% Debentures of ₹ 100 each ₹ 10,00,000; Fixed Assets at cost ₹ 22,50,000; Accumulated Depreciation on Fixed Assets up to date ₹ 2,50,000; Current Assets ₹ 12,00,000; Current Liabilities ₹ 4,00,000.