D +A = 50
A + A + A = 120
D + C = 35
C = ?

I am going fast, and I am standing still. I am transferring people and things all over the word. I have seats but I can’t fly. I make a sound that kids would like. 
What am i?

A man had a rare book worth several million, but he burned it on purpose.
Why?

What can you break, even if you never pick it up or touch it?

A says, “B is lying, and C is not.”
B says, “A is lying.”
C says, “I’m not lying, and I know D is lying.”
D says, “A and B are lying.”
E says, “B and D are not lying.”
There are three liars. Find them.

There are 8 brothers in the family, each of them have one sister. 
How many children are there in the family?