Final answer:
To find the total cost of the guitar with sales tax, multiply the price $129 by the sales tax rate 0.06 to get the sales tax amount $7.74, then add it to the original price, which totals to $136.74.
Step-by-step explanation:
To calculate the total cost of Karlene's guitar purchase including sales tax, first, we need to determine the amount of sales tax. We do this by converting the sales tax percentage into a decimal and then multiplying it by the original price of the guitar.
Calculation:
Convert the 6% sales tax to a decimal: 6% = 0.06
Multiply the sales tax rate by the original price: 0.06 × $129 = $7.74
Add the sales tax to the original price to find the total cost: $129 + $7.74 = $136.74
The total cost of the guitar after including the 6% sales tax is $136.74.