It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

Can you count the number of triangles in the given figure?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

The dirtier I get, the whiter I look. Who am I?

Which alphabet is a part of our body?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

When we see 2 but call 10?

What is the next shape from answers A, B, C, and D figure?

My location can be determined by the below rebus.
So where am i ?