1. consider all the possibilities, 2. Arrange or combine, 3. Express all the possibilities and add them.

So:

1. Two groups can be 3 and 3, 2 and 4, but not 1 and 5; 2. It is a combination, and there is no arrangement.

3. There are three people in both groups: because there are only two girls, it is impossible for girls to form a group alone, so the work arrangement is C6, 3; And 3; When the two groups are 4 +2 people, there is only one possibility for girls to be grouped alone (only 2 girls), so the work arrangement is C6,2-1+0. Add up: C6,3 3+C6 C6,2-1.