To find the percentage of the purchase price that was sales tax, you can use the formula:
\[ \text{Percentage} = \left( \frac{\text{part}}{\text{whole}} \right) \times 100 \]
In this case:
- The part is the sales tax amount, which is \( $10.28 \).
- The whole is the total purchase price, which is \( $128.50 \).
Now, substituting these values into the formula:
\[ \text{Percentage} = \left( \frac{10.28}{128.50} \right) \times 100 \]
Calculating the fraction:
\[ \frac{10.28}{128.50} \approx 0.07994 \]
Now, multiply by 100 to find the percentage:
\[ \text{Percentage} \approx 0.07994 \times 100 \approx 7.994 \]
Rounded to two decimal places, the sales tax percentage is approximately:
\[ \text{Percentage} \approx 8.00% \]
So, the sales tax is approximately 8.00% of the purchase price.