1. **Problem statement:** We are given the cost of a phone case in Chinese Yuan (¥28), an exchange rate ($1 = ¥7.17), and a tariff of 15%. We need to find the total cost per phone case in dollars after applying the tariff and then calculate the percentage profit if the phone case sells for $6.45. 2. **Convert the price of one phone case to dollars:** The formula to convert from Yuan to dollars is: $$\text{Price in dollars} = \frac{\text{Price in Yuan}}{\text{Exchange rate}}$$ So, $$\text{Price in dollars} = \frac{28}{7.17}$$ 3. **Calculate the price in dollars:** $$\frac{28}{7.17} \approx 3.905$$ Rounded to the nearest cent: $$3.91$$ 4. **Apply the 15% tariff:** The tariff increases the cost by 15%, so the total cost is: $$\text{Total cost} = \text{Price in dollars} \times (1 + 0.15)$$ Substitute the value: $$3.91 \times 1.15 = 4.4965$$ Rounded to the nearest cent: $$4.50$$ 5. **Calculate the percentage profit:** The selling price is $6.45, and the cost price including tariff is $4.50. Profit = Selling price - Cost price $$6.45 - 4.50 = 1.95$$ Percentage profit formula: $$\text{Percentage profit} = \left(\frac{\text{Profit}}{\text{Cost price}}\right) \times 100$$ Substitute values: $$\frac{1.95}{4.50} \times 100 = 43.333...$$ Rounded to the nearest whole number: $$43\%$$ **Final answers:** - (b) Total cost per phone case after tariff: $4.50 - (c) Percentage profit: 43%