Seven mobsters have arrived at the theater for the premiere of the film “Goodbuddies.” One of the mobsters, Frankie, is an informer, and he's afraid that another member of his crew, Joey, is on to him. Frankie, wanting to keep Joey in his sights, insists upon standing behind Joey in line at the concession stand, though not necessarily right behind him. How many ways can the seven arrange themselves in line such that Frankie’s requirement is satisfied?
Select the correct option
A) 1620	B) 1820	C) 2320	D) 2420	E) 2520
7 mobsters can stand in 7! ways = 5040   in half of the cases one person will be ahead and in the other person in the other half.   thus   5040/2= 
<gadget id="calculator">  5040/2</gadget>
<output>2_520</output>
2520 cases.   2520
<result>E</result>
Seven mobsters have arrived at the theater for the premiere of the film “Goodbuddies.” One of the mobsters, Frankie, is an informer, and he's afraid that another member of his crew, Joey, is on to him. Frankie, wanting to keep Joey in his sights, insists upon standing behind Joey in line at the concession stand, though not necessarily right behind him. How many ways can the seven arrange themselves in line such that Frankie’s requirement is satisfied?