1. **Problem Statement:** Calculate the profit or loss when an item is bought for 100 and sold for a certain price. 2. **Formula:** - Profit = Selling Price (SP) - Cost Price (CP) - Loss = Cost Price (CP) - Selling Price (SP) 3. **Important Rules:** - If SP > CP, there is a profit. - If SP < CP, there is a loss. 4. **Example:** Suppose the selling price is 120. 5. **Calculation:** - Profit = 120 - 100 = 20 6. **Explanation:** Since the selling price is greater than the cost price, there is a profit of 20. 7. **Final Answer:** Profit = 20