A taxi fare calculation system works by combining a fixed base fare with charges for both distance and time. 
The passenger pays a starting fee, then the kilometers traveled are multiplied by a per‑kilometer rate to add the distance cost.
At the same time, the minutes spent in the ride are multiplied by a per‑minute rate to add the time cost.
These amounts are added together with the base fare to give the total fare. 
In practice, rules such as minimum fare, waiting charges, night or holiday surcharges, and discounts for long trips can also be included to make the system more realistic.