Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

A red house is made out of red bricks. A yellow house is made out of yellow bricks. And, a blue house is made out of blue bricks. So, what is a greenhouse made of?

I look at you, you look at me I raise my right, you raise your left. What am I?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

There are 3 apples in the basket and you take away 2. How many apples do you have now?

I was speeding and ran through a stop sign, yet two traffic officers who were there do nothing about it.

why?

Akbar summoned Birbal out of anger.
He told him that he will have to face death.
He asked him to make a statement and if the statement is true he will be buried alive and if the statement is false, he will be thrown at lions.
After hearing Birbal’s statement, Akbar could do nothing but smile.
He gave him 5 gold bars and let him go.

What did Birbal say?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

Before Mount Everest was discovered, what was the highest mountain in the world?