Explanation: 20% marked up price এ product টি 500 টাকায় sell হবে. So if selling price is 120, cost price is 100. So, if selling price is 500, cost price is 416.66. So total cost price = \(416.66 * 120 = 50,000\). Now, total income = \(500 * 108 + 12 * 50\% * 416.666 = 54,000 + 2,500 = 56,500\). So profit = \(56,500 - 50,000 = 6,500\). So in percentage, \(\frac{6,500 \times 100}{50,000} = 13\%\).