Six 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 six arrange themselves in line such that Frankie's requirement is satisfied?

• 6
  
  24
  
  120
  
  360
  
  720

I am not able to understand the combinations to be subtracted. Would be helpful, if someone can present the solution with the Glue method described in Manhattan strategy guides?