What is always in front of you but can’t be seen?

Two friends decide to get together; so they start riding bikes towards each other. They plan to meet halfway. Each is riding at 6 MPH. They live 36 miles apart. One of them has a pet carrier pigeon and it starts flying the instant the friends start traveling. The pigeon flies back and forth at 18 MPH between the 2 friends until the friends meet.

How many miles does the pigeon travel?

How many minutes are there in Feb 2017?

Note: The shortest answer is the correct answer.

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Before Mount Everest was discovered, what was the highest mountain in the world?