consider naming all teams from A to H.
Now each teams plays with other twice .
so A plays with B , C ... H.
these are 7 matches .
we need not put the second condition right now , that there are 2 matches between each team .
Team B plays with A,C,D....H.
Total 7 matches .
similarly all 8 teams play 14 matches but each match has 2 teams so remaining is 7 .
multiply no. of teams answer