The total amount of tax on her purchases to the nearest cent will be $9.97
Explanation
Marcella Heinz purchased office supplies for $107.64 and then she purchased an English-Spanish dictionary for $16.95
So, the total amount of her purchases [tex]=\$107.64+\$16.95=\$ 124.59[/tex]
On the total amount of the purchases, she paid state sales tax of 7.5% and the county tax of 0.5%
So, the amount of the state sales tax [tex]=\$124.59*7.5\%= \$124.59*0.075=\$9.34425[/tex]
and the amount of county tax [tex]=\$124.59*0.5\% =\$124.59*0.005 = \$0.62295[/tex]
Thus, the total amount of tax on her purchases [tex]=\$9.34425+\$0.62295= \$9.9672 \approx 9.97[/tex] (Rounded to the nearest cent)