Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

Solve the mathematical equation in the picture below.

Solve the puzzle by telling what does below picture means.

How can you make number one disappear by adding something to it?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

What Time Should the last watch show in the below figure?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

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?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99