Alicia took a friend to dinner for her birthday. The total bill for dinner was $30.69 (including tax and a tip). If Alicia paid a 21.5% tip, what was her bill prior to adding the tip?

The original bill was $25.26

Step-by-step explanation:

To find the original bill, you need to divide the amount paid by the percentage paid. Since the tip was 21.5% on top of the full amount already, we know she paid 121.5%. So we can divide the cost by that.

$30.69/121.5% = $25.26