Let the tax rate be x%x%. We know that when the before-tax price of $92$92 is added to the product of the tax rate and $92$92, we get the after-tax price of 98.9098.90. So,

92+x100∗92=98.900.92x=98.90−92x=6.900.92=7.592+x100∗92=98.900.92x=98.90−92x=6.900.92=7.5

Thus, the tax rate is 7.5%7.5%.