Can it be possible to build a house that has all its four walls facing towards the South?

Given below is simple addition with a defined pattern pattern:
7 + 7 = 2
8 + 8 = 4
8 + 5 = 1
6 + 9 = 3
10 + 11 = 9

Can you analyze the pattern and find out the answer for:

4 + 9 = ?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?

What word is pronounced the same if you take away four of its five letters?

What always comes into a house through the keyhole?

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

Where do fish keep their money?

Who is that with a neck and no head, two arms and no hands? What is it?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?