To calculate the amount of sales tax charged on the repaired computer at Store A, you can use the following formula:
\[ \text{Sales Tax} = \text{Price} \times \text{Sales Tax Rate} \]
From the table, the price of the computer repair at Store A is $1,200, and the sales tax rate is 6 percent (0.06 in decimal form).
\[ \text{Sales Tax} = 1,200 \times 0.06 = 72 \]
Therefore, the amount of sales tax charged on the repaired computer at Store A is $72.