Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

If it took eight men ten hours to build a wall, how long would it take four men to build it?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Our product and our sum always give the same answer. Who are we?

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?

Can you solve this picture maths equation?

A journalist was investigating a sacred cult in the jungles of Africa when he was caught by one of the person. He was confined in a cave till the leader arrived. The leader told him that he need to tell him a statement. If he thinks the statement is true, then the journalist head will be chopped off. If he thinks that the statement is false, his head will be smashed with a hammer.

What statement did the journalist make to survive?

Two old friends, Jack and Jill, meet after a long time, and discussing as:

Jack: Hey, how are you, man?

Bill: Not bad, got married and I have three kids now.

Jack: That's awesome. How old are they?

Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.

Jack: Cool..But I still don't know.

Bill: My eldest kid just started taking piano lessons.

Jack: Oh, now I get it.

How old are Bill's kids?

Take number 1000 and then add 20 to it.
Now add 1000 one more time.
Now add 30.
Now add 1000 one more time.
Now add 40.
Now add 1000 one more time.
Now add 10.

What is the total?

I have an eye but still cannot see.

Who am I?