Can you explain this step by step?

Combination permutation
Ash and Bradley don't like each other so they don't like sitting with each other. There are two circular tables, one with 4 people and one with 8 people. How many combinations ate there?

Say Ash sits at table A.

There are 10 other people who can sit with her (not counting Bradley), so that makes
10C3 = 120 ways to pick them
Once they are chosen, everyone else sits at table B, so that's that.
Of course, Bradley could sit at table A, so I guess that makes another 120 combinations for him.

Thanks for the reply but where is 3 from