What does below pictogram mean?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

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

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

John was drowned by he was not wet. How?

Two Twins Jack and Jill were standing back to back and suddenly they started running in opposite direction for 4 kilometres and then turn to left and run for another 3 kilometres.

what is the distance between the Baggio twins when they stop ?

How do you go from 98 to 720 using just one letter?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

No matter how little or how much you use me, you change me every month. What am I?