A restaurant bill, including an 8% tax, totals $70.20. What was the pre-tax amount of the bill, in dollars?

The $70.20 total includes the 8% tax, so it equals 108% of the pre-tax amount. Write $1.08p = 70.20$ and divide: $p = \frac{70.20}{1.08} = 65$. Check: 8% of $65 is $5.20, and $65 + 5.20 = 70.20$. A common wrong answer is 64.58, which comes from subtracting 8% of the total, $70.20 \times 0.92$. That treats the tax as a percent of the final bill instead of the original amount. Another wrong answer is 62.20, from subtracting 8 dollars instead of 8 percent. Reverse a percent increase by dividing by the multiplier.