Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

You need to move three matchsticks to form three squares. Can you do it?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

What has one letter and starts with an E?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.

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

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

John was drowned by he was not wet. How?