Replace the question mark with the correct number in the below-given picture?

Find out the missing number in the picture attached:

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

You can hear me, but you can't touch or see me.

What am I?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

In a stable, there are men and horses. In all, there are 22 heads and 72 feet. How many men and how many horses are in the stable

How can you take 2 from 5 and leave 4?

What will you call your mother's brother's brother-in-law?

Which Burger Is Different in below image?

Three people check into a hotel. They pay $60 for the rent of the room. After they check-in, the manager realize that the rent for the room is $55. So, he gives $5 to the bellboy and asks him to give it to them. The bellboy thinks that it will be difficult for the three people to share $5 among them and seeking the personal benefit, he pockets $2 and gives the remaining $3 to them.

Now, each person paid $20 and got back $1. In this manner, each of them paid just $19 which totals to the amount of $57. The bellboy has $2 with him and adding them, we get $59. So where is the remaining $1?