Let's call the seats A,B,C,D,E,F,G
Then, the possibilities for the chair positions for the three people are :
A C E B D F C E G
A C F B D G
A D F B E G
And each of the three people can be assigned to these seats in 3! ways = 6 ways
And the other 4 people can be arranged in 4! ways = 24 ways for each arrangement above
So we have
7 position possibilities * 6 arrrangements of the three people for each position possibility* 24 arrangements of the other 4 people = 1008 ways
As Melody often says....."That's what I think"
