Final answer:
To calculate the price of the toy robot after tax, multiply the original price by the tax rate and then add the tax to the original price.
Step-by-step explanation:
To calculate the price of the toy robot after tax, we need to add the tax to the original price. First, convert the tax rate of 9% to a decimal by dividing it by 100: 9/100 = 0.09. Next, multiply the original price of $129 by the tax rate: $129 * 0.09 = $11.61. Finally, add the tax to the original price: $129 + $11.61 = $140.61.