Final answer:
The total cost of the outfit, including sales tax, is $91.56.
Step-by-step explanation:
The total cost of the outfit can be found by adding the original cost and the sales tax. In this case, the original cost of the outfit is $84. The total cost of the outfit, including sales tax, is $91.56.
To find the sales tax, convert the tax rate of 9% to a decimal by dividing by 100 (9/100 = 0.09). Then, multiply the original cost by the sales tax rate to find the amount of tax ($84 * 0.09 = $7.56). Finally, add the original cost and the tax to find the total cost of the outfit ($84 + $7.56 = $91.56).
Therefore, the total cost of the outfit, including sales tax, is $91.56.