Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

I have branches, but no fruit, trunk or leaves. What am I?

What does this rebus mean?

O
N
C
E
TIME

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

What is the below Rebus indicate?

Can you decipher the below rebus?

PBLUESAISNUERSES

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

10 people came into a hotel with 9 rooms and each guest wanted his own room. The bellboy solved this problem.
He asked the tenth guest to wait for a little with the first guest in room number 1. So in the first room, there were two people. The bellboy took the third guest to room number 2, the fourth to number 3, ..., and the ninth guest to room number 8. Then he returned to room number 1 and took the tenth guest to room number 9, still vacant.
How can everybody have his own room?

John was piloting a plane behind a car but was never able to overtake it. Why?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?