Why are opposite X-M-X angles not counted in MX6 octahedral geometry?

[mooncrater]

Homework Statement

The question says:
Find the number of X-M-X angles in MX₆, which has an octahedral geometry.

Homework Equations

None

The Attempt at a Solution

To do this question , I used p&c .
Since there are 6 X in MX₆ and we have to choose two of them . Therefore total number of M-X-M bonds will be ⁶C₂=15.
But the solution says that it is 12. When I saw it , I noticed that they had missed the opposite M-X-M bonds. So why had they(the solution makers) not counted those bonds? Are they wrong here ?

 

[Borek]

I can't think of a good answer to your question. We typically speak only about angles between adjacent bonds, but technically counting angles between non-adjacent bonds is not a mistake if the question is worded just "count angles between bonds".