Which number should replace the question mark?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A man is shown a portrait painting. He looks closely, then tells, “Brothers and sisters have I none, but that man’s father is my father’s son!” Who is the man in the portrait?

Be active and find the killer in the picture Riddle below.

Can you make a six-letter word using the letters N, A and B ?

John said, "If yesterday was tomorrow, today would be Friday."

When did John make this statement?

On a bright sunny day, two fathers took their son fishing in the lake. Each man and son were able to catch one fish. When they returned to their camp, there were only three fishes in the basket. What happened?

PS: None of the fish were eaten, lost, or thrown back.

What is more useful when it is broken?

I am white when I am dirty, and black when I am clean. What am I?

John is the son of Jacob.
So,
Jacob is the_____of John's father?