Suppose there are three passengers sharing a single cab ride and that passenger A’s usual fare to his destination would be $12, passenger B’s usual fare to her destination would be $18, and passenger C’s fare would be $30. Since they are sharing the cab, and assuming no surcharge, the total cab fare is $30, rather than the $60 they would have pay in total individually. So there is a $30 saving to sharing the cab.

Required
How would you split up the total cost of the cab fare among A, B, and C?