Adding Filter(s) to Divide Calculation

Hi All, 

I'll try my best to explain this but I currently have a relatively simply divide calculation in place to work out a cost per kg. This works fine with my visuals to an extent however I would also like to take in to account other factors such as destination and airline to give me an overall value of cost per kg based on these selections made in visuals.

At the moment if I select a destination for example then yes the other visual will display the airlines utlised on these destination but that gives me an overall cost per kg based on ALL airlines. If I then go to select one of these airlines then I will get all destinations serviced by that airline and so on rather.

Hoping that makes sense but welcome further questions!

Thanks,