Let x be the percentage of the sales tax rate as a decimal number, then we can set the following equation:
[tex]360x=21.60.[/tex]Dividing by 360 we get:
[tex]\begin{gathered} \frac{360x}{360}=\frac{21.60}{360}, \\ x=0.06 \end{gathered}[/tex]Therefore, the sales tax rate as a percentage is 6%.
Answer: 6%.
