Monthly Salik cost depends entirely on how many toll gates your regular route crosses and how many times per day, not on distance travelled. A commute crossing two gates each way, five days a week, adds up to roughly 88 gate crossings a month once the round trip and full working month are calculated - multiplied by the current per-crossing rate. Routes avoiding gates entirely incur no Salik charge regardless of distance, while a short route through multiple gates can cost more than a longer gate-free alternative.
Check your own exact figures with the Salik Toll Cost Calculator - free, in under a minute, no sign-up required.