1. **State the problem:** A store buys a skateboard for 70 and applies a 15% markup. We need to find the selling price. 2. **Formula:** Selling Price = Cost Price + Markup Markup is calculated as a percentage of the cost price: $$\text{Markup} = \text{Cost Price} \times \frac{\text{Markup Percentage}}{100}$$ 3. **Calculate the markup:** $$\text{Markup} = 70 \times \frac{15}{100} = 70 \times 0.15 = 10.5$$ 4. **Calculate the selling price:** $$\text{Selling Price} = 70 + 10.5 = 80.5$$ 5. **Answer:** The selling price of the skateboard is 80.5.