Simon Tam is negotiating passage on Serenity as a clandestine fugitive from

the planet Persephone. He is told that the 185 million kilometer trip to Osiris
will cost $4,120. Alternatively, he can take a 365 million kilometer trip to
Bellerophon, but that will cost $7,360. If cost depends on distance, what is
the fixed cost, and what is the variable cost, of the voyage to Bellerophon?

Hi I am having trouble distinguishing what the variable cost would be, so if you could help me out that would be great!!