Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

Find the missing number in the image below.

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

On a magical land of Mexico , all the animal in the land are rational.

There are 10 tigers and one goat.
Tiger can eat goat but since it's a magical land , the tiger who eats the goat , turns into goat and then can be eaten by the remaining tiger(s).

If we leave them for some time then how many goat and tiger will be there , when we come back ?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

This was asked in an interview with Coa-Cola.

The interviewer has given me 100 marbles(50 white and 50 black) and two empty boxes.
He then told me that he will leave the room and i need to place all the marbles in two boxes.

And When he come back, he will draw a marble from any of the two box and if the marble is white I will be hired.

Also
* No box can be empty.
* All 100 marbles must be placed in one of the two boxes.

So what should I have done?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

There are three houses in a straight row. One is red, one is blue, and one is white. The red house is left of the middle. The blue house is right of the middle. Where's the white house?