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

Can you find out the number that should replace the question mark with a valid reason?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see? What is it?

What can you hold in your right hand, but never in your left hand?

Take one out and scratch my head, I am now black but once was red. What am I?

What has 88 keys?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?

I make two people out of one. What am I?

There are 4 big houses. They are made from the materials: red marble, green marble, white marble and blue marble.

* Mrs Jennifer's house is somewhere to the left of the green marble one and the third one alone is white marble.
* Mrs Sharon owns a red marbles house and Mr Cruz does not live at either end, but lives somewhere to the right of the blue marbles house.
* Mr Danny lives in the fourth house, while the first house is not made from red marble.

Who lives where, and what is their house made from?