1. **State the problem:** Calculate the final price of a shirt originally priced at 80 with a 20% discount, then an additional 10% coupon discount on the sale price, and finally a 5% sales tax on the discounted price. 2. **Formula and rules:** - Discounted price after a percentage discount: $$\text{Price after discount} = \text{Original price} \times (1 - \text{discount rate})$$ - Sales tax added: $$\text{Final price} = \text{Price after all discounts} \times (1 + \text{tax rate})$$ 3. **Calculate the sale price after 20% discount:** $$\text{Sale price} = 80 \times (1 - 0.20) = 80 \times 0.80 = 64$$ 4. **Apply the 10% coupon discount on the sale price:** $$\text{Price after coupon} = 64 \times (1 - 0.10) = 64 \times 0.90 = 57.6$$ 5. **Calculate the final price including 5% sales tax:** $$\text{Final price} = 57.6 \times (1 + 0.05) = 57.6 \times 1.05 = 60.48$$ 6. **Answer:** The final price of the shirt including all discounts and tax is **60.48**. Therefore, the correct choice is **C) 60.48**.