Step 1
State the for the sales tax rate
[tex]\frac{sales\text{ tax}}{cost\text{ of item before tax}}[/tex]where
[tex]\begin{gathered} \text{sales tax=\$37.80} \\ \cos t\text{ of the item before tax=\$420} \end{gathered}[/tex]Step 2
Get the sales tax rate in percentage by substitution
[tex]\begin{gathered} =\frac{37.80}{420}=0.09 \\ \text{Convert to percentage} \end{gathered}[/tex][tex]\begin{gathered} 0.09\times100=9^{}\text{\%} \\ \end{gathered}[/tex]