I need help understanding the following question. I don't know whether to add the tax to the price or subtract it.

Air, Inc. has provided the following information:

• Dividend per share $8.50
• Current stock price $83 per share

In the current environment capital gains are not taxable, but dividends are taxed at 18 percent. New IRS guidelines require that taxes be withheld when the dividend is paid.

The stock is going ex-dividend tomorrow. What is the ex-dividend price of the stock?