Average Speed of Ali's trip

An easy puzzle to start your day with:

There was a salesman named, Ali. Who had to drive to city B to sell his products. Ali is currently at location A. He can drive at different speeds throughout the journey.

For, the first half of the distance of his journey, he decided to travel it with an average speed of 80 km/h. (km/h means kilometres per hour). In this half of the journey, he doesn't change his speed in between. Rather, the speed stays the same throughout the first half, which is equal to 80 km/h.

After, finishing the first half of the journey, he travels the next half of the trip with a constant speed of 120 km/h. Now, we have to find, the average speed of Ali, for the whole journey?

Now, if we also include the return journey from City B to City A. Where, Ali travels at the speed of 80 km/h throughout the journey. What can be said about his round trip average speed? Can we know exact round trip average speed of Ali or we need the distance parameter specified in the question to find the average speed?

All the discussion of this puzzle, I leave it to your brain. Make cells of your brain fight for the answer. I have faith in you all LLs. You will surely get to the answer. See you all. All the best to solve the puzzle. I will be there, after sometime with another interesting puzzle. Till then, good bye.

An Easy One:
A salesman drives from A to B. The first half of the distance of his journey, he drives at constant speed of 80 km/h and the second half of his journey, he drives at a constant speed of 120 km/h. What is the salesman's average speed for the complete journey?

Bodmas and his students

Mr. Bodmas is the known maths wizard who was able to solve any number mysteries within a fraction of time. He was mainly known for his invention about the rules of calculation patterns. The rule itself is known as BODMAS rule. The full form of it is: BRACKETS OF DIVISION MULTIPLICATION ADDITION SUBTRACTION. The rule says that when we found all these things into a formula, from where to start the calculation. ie, we first solve the equation within the brackets. So, Brackets have the highest priority. Then in the descending order of priority comes, Division, Multiplication, Addition and Subtraction.

This wizard had three of his students who were grasping each and every concepts of numbers easily. He wanted to test their abilities. So, he handed each of them a sealed envelope with a number written inside. He told all of them that they each have a positive integer written inside the envelope.  And, the sum of all the integers is 14.

They each opened the envelope and inspected their numbers. The task for them was to find the numbers written on others' envelopes. To reach a conclusion these three students say:

The names of these three students are: Amit, Shashi and Rahul.

Amit says(after seeing his envelope) : "I know that Shashi and Rahul each have a different number."
Shashi says: "I already knew that all three of our numbers were different."

After listening to these two speak,
Instantly, Rahul says: "Now I know what all three of our numbers are."

How can Rahul know what the numbers of others are? And what are those numbers?

By that, I leave this puzzle in your brain muscles to be solved. I will wait for your answer. The puzzle needs some deep thinking, but this puzzle doesn't require any complex concepts of numbers. So, give yourself a try and solve it.