Answer:

Minimum number of rooms required = ???????????????????? ???????????????????????? ???????? ???????????????????????????????????????????????? / ???????????? (60,84,108)

Prime factorization of 60, 84 and 108:

60 = 2² × 3 × 5

84 = 2² × 3 × 7

108 = 2² × 3³

HCF = 2² × 3

HCF = 12

Total number of participants = 60 + 84 + 108 = 252

So, the minimum number of rooms required = 252/12 => 21

Hence, the minimum number of rooms required is 21.