1. **Problem:** Find the percentage profit on the following items. 2. **Formula for percentage profit:** $$\text{Percentage Profit} = \left(\frac{\text{Selling Price} - \text{Cost Price}}{\text{Cost Price}}\right) \times 100$$ 3. **Important rule:** Profit occurs when the selling price is greater than the cost price. 4. **Calculations:** - a. Watch: Cost price = 50, Selling price = 65 $$\text{Profit} = 65 - 50 = 15$$ $$\text{Percentage Profit} = \left(\frac{15}{50}\right) \times 100 = 30\%$$ - b. Phone: Cost price = 300, Selling price = 360 $$\text{Profit} = 360 - 300 = 60$$ $$\text{Percentage Profit} = \left(\frac{60}{300}\right) \times 100 = 20\%$$ - c. Tablet: Cost price = 500, Selling price = 600 $$\text{Profit} = 600 - 500 = 100$$ $$\text{Percentage Profit} = \left(\frac{100}{500}\right) \times 100 = 20\%$$ - d. Necklace: Cost price = 400, Selling price = 460 $$\text{Profit} = 460 - 400 = 60$$ $$\text{Percentage Profit} = \left(\frac{60}{400}\right) \times 100 = 15\%$$ 5. **Final answers:** - Watch: 30% - Phone: 20% - Tablet: 20% - Necklace: 15%