To determine the sales tax percentage, we can follow these steps:
- Calculate the amount of sales tax paid.
- Divide the sales tax by the original price of the item.
- Convert that decimal into a percentage.
Step 1: Calculate the sales tax amount: \[ \text{Sales Tax} = \text{Total} - \text{Cost of Item} = 781 - 710 = 71 \]
Step 2: Find the sales tax rate as a decimal by dividing the sales tax by the original price: \[ \text{Sales Tax Rate} = \frac{\text{Sales Tax}}{\text{Cost of Item}} = \frac{71}{710} \]
Calculating it: \[ \frac{71}{710} = 0.1 \]
Step 3: Convert the decimal to a percentage: \[ \text{Sales Tax Percentage} = 0.1 \times 100 = 10% \]
Therefore, the sales tax percentage is \( \boxed{10%} \).