Circumference of 1 table:
C = πd = 140π = 439.82 cm
Each person needs 60 cm, so divide the circumference by 60 to find the number of people who can sit at each table.
439.82/60 = 7.33
So at most 7 people can sit at each table.
7*12 = 84 so the room can only hold 84 people.
You're right