Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

A king sentenced a man to the death sentence for some crime he had committed. Known for his kindness, the king told the culprit that he had a choice to die in a way he decides.

The culprit was clever and said something that saved him from death. What method do you think he must have chosen for his death?

What can you catch but never throw?

One day, John and his friends were playing around. Jacob hit something with a Pin and it popped. John's dad came into the room that very moment, but he wasn't mad. In fact, he was smiling. What did Jacob hit?

Rearrange the letters in "new door" to make one word.

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

What occurs twice in a week, once in a year but never in a day?