Instead of solving for the fixed charge and rate separately, compare the two given trips directly. Going from 10 km to 15 km, the distance increases by 5 km and the fare increases from Rs. 150 to Rs. 220, an increase of Rs. 70. So the variable rate per km is:
\[\frac{70}{5}=14 \text{ Rs./km}\]
Now extend the 15 km trip (Rs. 220) to 25 km, an increase of 10 km:
\[220 + 10\times14 = 220+140 = 360\]
Since the fixed charge cancels out when comparing trips, the fare for 25 km works out to Rs. 360 without needing to find the fixed charge separately.
Hence, the correct answer is Option C: Rs. 360.