Hello!
[tex]\large\boxed{9 \%}[/tex]
To find the percent tax, use the equation:
[tex]\text{ \% tax} = \frac{\text{ price after - initial price}}{\text{initial price}}[/tex]
Substitute in the given values:
[tex]\text{ \% tax} = \frac{\text{ 21.80 - 20}}{\text{20}} \\\\\text{ \% tax} = \frac{1.80}{20} = 0.09[/tex]
Multiply by 100 to find the percent tax:
[tex]0.09 * 100 = 9\%[/tex]
