First, find how much Justine paid in tax. To do this, first convert 13% to a decimal by dividing by 100. This gets a tax rate of 0.13. Now, multiply the price of the boots by the tax rate. 76.68*0.13 = 9.9684. Round to the nearest cent to get $9.97.
Now, add the amount paid in tax to the price of the boots. 76.68+9.97 = $86.65.