There are two venues for 18 teams to participate in the football match. Please write down the rules of grouping and drawing lots.

20÷4=5 teams in each group, each group plays 4+3+2+ 1= 10, and one * * * plays 10×4=40 games.

2.A * * * 2×4=8 teams entered the second round. Because of the elimination system, eight teams eliminated seven teams, so there will be seven games.

8- 1=7 games