Sorry, unable to find paper but from memory . . .
Albert Bertha Charlie and Dan go out to dinner. Albert must sit facing south to have a sea view and Bertha and Charlie always sit next to each other.
How many seating combinations are there?
After a few days, Charlie agrees to do without the sea view. How many further seating combinations are there?
If Bertha and Charlie can sit apart from each other, how many seating arrangements are possible?
Such possibilties can also fit with sandwiches and garnishes etc
May not be that onerous to work out by simply repeated table plans, and perhaps this OK in answer as long as done in orderly fashion but I would like to know on a personal level how to approach it from a mathematical view point