Let's start by finding the head start of the bus, i.e., how far it traveled between 9:20am and 9:40am.
Time taken by the bus = 9:40am - 9:20am = 20 minutes = 1/3 hour
Distance traveled by the bus in 1/3 hour = speed x time = 75 x 1/3 = 25 km
So, when the taxi started at 9:40am, the bus was already 25 km ahead of it.
Now, let's find out how long it takes for the taxi to catch up with the bus.
Let t be the time taken by the taxi to catch up with the bus after 9:40am.
Distance traveled by the bus in t hours = distance traveled by the taxi in t hours + 25 km
75t = 95t + 25
20t = 25
t = 5/4 hour
So, the taxi catches up with the bus 5/4 hour after 9:40am, which is at 10:05am.
Now, let's find the distance covered by the taxi by 10:05am.
Distance covered by the taxi in 5/4 hour = 95 x 5/4 = 119 km
Therefore, the distance covered by the taxi from the petrol station when it caught up with the bus was 119 km.