Explanation:
There are different possible explanations for this scenario. Here are some of them:

1. Different routes:
It's possible that the bus takes a different route when it goes from Dibrugarh to Assam compared to when it comes back. This could be due to a number of factors such as traffic, road conditions, or construction work. The different route could be shorter or longer, which could explain the difference in travel time.

2. Speed:
Another possibility is that the bus travels at a different speed when it goes from Dibrugarh to Assam compared to when it comes back. This could be due to the time of day, traffic conditions, or driver behavior. For example, the driver may be more cautious when driving uphill compared to downhill.

3. Stops:
It's also possible that the bus makes different stops when it goes from Dibrugarh to Assam compared to when it comes back. For example, the bus may make more stops to pick up passengers when going from Dibrugarh to Assam, which could increase the travel time.

4. Time zone:
Finally, it's possible that the difference in travel time is due to a change in time zone. For example, if Assam is in a different time zone compared to Dibrugarh, the bus may appear to take longer to travel from Assam to Dibrugarh compared to the return journey, even though the actual travel time is the same.

In conclusion, there are several possible explanations for why the bus takes 90 minutes to go from Assam to Dibrugarh but 1 hour and 30 minutes to come back. It's important to consider all the factors that could be affecting the travel time before coming to a conclusion.

A bus takes to go = 90 minutes and to come back it takes 1 hour and 30 minutes. therefore we know that 1hour=60minutes, now we need to add 60 and 30 that's 90 minutes, so we can say that 90 minutes= 1hour and 30 minutes right .