1. The problem is to understand and use the discount formula to calculate the discounted price of an item. 2. The discount formula is: $$\text{Discounted Price} = \text{Original Price} - (\text{Original Price} \times \text{Discount Rate})$$ or equivalently: $$\text{Discounted Price} = \text{Original Price} \times (1 - \text{Discount Rate})$$ where the discount rate is expressed as a decimal (for example, 20% discount means 0.20). 3. Important rules: - Always convert the percentage discount to a decimal before using it in the formula. - The discount rate must be between 0 and 1. 4. Example: If an item costs 100 and the discount is 15%, then: $$\text{Discounted Price} = 100 \times (1 - 0.15) = 100 \times 0.85 = 85$$ So, the price after discount is 85. This formula helps you find the price after applying any percentage discount.