The answer is in the link below I couldn't write it on Brainly bc my computer was being wack, but I hope I can help, I didn't only give the answer but there is a step by step so that should help you out a bit. Good Luck!!!!!!
Circumference = πD
30π = πD
D = 30 inches
Answer: 30 inches
18 ? am not really sure tho its kinda difficult lol
4 tables. 4*4 is 16, meaning that even if 4 players want to sit together it doesn't make a difference. With 16 players and 4 at a table we are going to need 4 tables.