You would want to have more than 61% of the seats available for a smoke free area.
61% = 0.61 0.61 * 149 = 90.89 or 91 seats to accommodate 61% smoke free customers
To allow for any extra customers in a smoke free area I would figure on 65%
so 65% = 0.65 0.65 * 149 = 96.85 or 97 seats to allow for a few extra for the customers in the smoke free area