The number of games played is given by n(n-1)/2. For 10 players, it is 10(10-1)/2 = 45.

The number of games played is given by n(n-1)/2. For 12 players, it is 12(12-1)/2 = 66 games.

The number of games played is given by the combination formula n(n-1)/2. For 10 players, it is 10(10-1)/2 = 45 games.

Given that A cannot sit next to B, and C must sit next to D, the only option left for A is to sit next to C.

If A is next to B and C is opposite A, the only person who can be next to C is D.

G is to the left of H, and I is to the right of G. Therefore, both G and I are sitting next to H.

Since A is next to B and C is opposite A, D must be next to C.

The arrangement can be visualized as H-G-I-J-K-L. Therefore, H is sitting next to J.

With G to the left of H and I opposite G, we can deduce that J is to the right of H.

Since A is next to B and C is opposite A, the arrangement shows that D must be next to C.

By placing A and B in the arrangement, we can deduce the positions of C, D, and E. The person opposite B will be D.

The arrangement can be visualized as A-B-D-C-E-F. Therefore, E is sitting opposite to B.

Since Z is opposite X, the arrangement shows that A and B must be next to Z, but since X is next to Y, C must be next to Z.

Arranging A, B, and C, we can deduce that F is sitting opposite B.

With F between G and H, and I opposite G, H must be next to I.

Since G is between H and I, the person sitting next to I must be G.

M is between N and O, which means N is next to O. P is opposite M, so the only person next to O is N.

With M to the left of N and O to the right of M, the arrangement can be completed to find that P is opposite N.

Since S is between T and U, U is sitting next to T.

The arrangement is Y-X-Z. Since W is opposite Y, the only person next to W would be Z.

Since C is opposite A, and A is next to B, the only person who can be next to C is D.

To find who is opposite B, we can visualize the arrangement. If A is left of B and C is right of A, then F must be opposite B.

By placing A and B, and C accordingly, we can determine that G is opposite A.

The arrangement is F-G-H. Therefore, H is sitting next to F.

With M between N and O, and P opposite M, Q must be sitting next to P.

If Q is to the left of R, then R is to the right of Q. S being opposite Q means R is also to the right of S.

The arrangement can be visualized as Y-X-Z-A-B-C-D. Therefore, Y is sitting next to A.

Since A is to the left of B, and C is opposite A, the arrangement can be visualized. If we place A at a position, B will be to the right of A, and C will be directly across from A. Therefore, D will be to the right of C.

Since A is to the left of B, B is to the right of A. C is opposite A, so the arrangement is A-B-D-C-E-F-G-H. Therefore, D is to the immediate right of B.

Since A is to the right of B, and C is opposite A, the arrangement can be visualized. If we place A and B, C will be directly across from A. The person to the left of C will be D.