What size tables are available at the venue? Once you know that, you can do the math. I think the 60" round tables are more common. If that is what was available then I'd put 8 people at 3 tables and 9 people at the other 3 tables.
Comfortable Seating For Rectangular Tables
24-inch x 60-inch table seats two people
24-inch x 72-inch table seats three to four people
24-inch x 96-inch table seats four to five people
30-inch x 72-inch table seats six people
30-inch x 96-inch table seats eight people
Comfortable Seating For Round Tables
36-inch table seats four people
42-inch table seats five people
48-inch table seats five people
54-inch table seats six people
60-inch table seats eight people
72-inch table seats 10 people