The number of ways in which 5 picturers can be hung from 7 picture nails on the wall is

In how many ways 7 pictures can be hung from 5 picture nails on a wall?

In how many ways 7 pictures can be hung from 5 picture nails on a wall?

In how many ways can 6 pictures be hung from 4 picture nails on a wall?

The number of ways in which 7 persons can sit around a rouund table is

The number of ways in which a 7 people can sit around a round table is

The number of ways in which 5 ladies and 7 gentlemen can be seated in a round table so that no two ladies sit together, is

In how many ways 7 pictures can be hanged on 9 pegs?